Hm. Okay, I'm gonna put my two bubbles in. It's just an opinion, so go easy on me.
I did my first dive in the summer of 1986. I sorta "played" with it for about 100 dives or so total through the '90's, and then got my first Open Water scuba certification in 2001 or 2002. I only did that because the "industry" got to the point where I couldn't fill a tank anymore without a certification.
That might seem reckless, and I suppose in hindsight it was... But I simply didn't have the option to go down to my local dive shop and get certified in 1986. Diving was, at the time, an unusual activity, and dive shops didn't exist on every corner. I did what I could to get wet - and that's all there was to it.
For what it's worth, I don't recommend doing that, if any non-diver considering becoming a diver is reading this. I would have taken the opportunity to learn from someone if I'd had the resources available to me... They simply weren't. Classes are fun and teach you some of the basics that I had to search high and low for in order to dive safely. Anyone ever heard of the World Book Encyclopedia? That was where I learned the basics. No kidding. That and the library. It's much easier today, with the availability of instructors and dive shops and certifying agencies and comparably inexpensive gear.
In 2003 or so, I started hearing this term "technical" diving... It was explained to me that the term meant, "Any diving outside the recreational dive limits," or, precisely, what the agencies were teaching. Immediately I understood that to mean, "below 130 or so feet" (depending on the agency you're talking about), and then thought it also included any kind of overhead diving, since that was very frowned opon by the agencies. This changed over time, with courses offered in penetration diving. Clearly, though, mixed gasses like "nitrox" and trimix were also "technical," because they often had the word "technical" right in the description.
Circa 2004 or so, I took a "Fundies" class from GUE - Mike Kane and Andrew G, to be specific. I took the class to prove to myself that the DIR guys really were a bunch of cult-minded, overzealous crazies that were taking this diving thing entirely too seriously. I wrote about the experience right here on Scubaboard, and it's been cited in many threads.
At the class, I asked Andrew G specifically if this "Fundies" class qualified as "technical" training. In fact, maybe it wasn't a question... I think I said something like, "I want to start 'tech' diving, so I figured that this was a good beginning point" when each of us stated why we were there. The truth is, I had simply heard so much about the course that I was curious... And very skeptical. The only reason that I was really there is because I was about to buy my first BC (I'd always rented or borrowed), and of course everyone here had told me that a bp/wing was the way to go - with the #1 cited advantage of it being that I couldn't take a "DIR" class if I chose anything else. Interest piqued, I spent the money to find out who these "n a z i s" were (I had joked with them and called them that - they didn't seem to have much sense of humor).
(For what it's worth, I found myself completely incorrect about my assumptions about the DIR concept, and started soon after to adopt DIR principles, based on my experience in the class. So before anyone attacks me... I must mention that I, myself, am a DIR convert. But I digress...)
Andrew G told me something right then and there that sticks with me to this day: There is no such thing as "technical diving." It's a misnomer.
As I have dived dive after dive over the past few years, I understand what he meant.
Nobody calls themselves a "technical motorist" if they can drive a stick shift. Sure... It's an additional skill that takes practice, and screwing it up can mean big bills or hurting yourself or others. People are killed every day in cars, yet we do not have a separate "kind" of driver's license for "technical drivers." ALL drivers are expected to be in control of their vehicles and obey the basic rules of the road - stay in your own lane, drive the speed limit or less, stop at the stop sign, green means go, etc. Sure, there's different skill sets (like commercial drivers, for example), but the basic rules are the same whether you're in New York City or Nowhere, Arizona (and yes, I have been to both).
Diving is diving, and that's all there is to it. Yes, sometimes it's best to have a 4 wheel drive, sometimes it's best to have a truck or van. Sometimes it's best to have a nice sports car, and everybody loves a classic. Regardless, all of these different vehicles operate the same way and all of the rules of the road - those mandated and assumed - apply no matter what you're driving.
In this way, I tire of hearing the "around here" diver talk about "these waters," as if they're completely different from all other water on Earth. No matter where you go, there's always an "around here" diver in the corner telling everyone who will listen that the rules of "normal" diving don't apply "around here," and that "these waters" are somehow different than all of the other waters everywhere else on Earth, so it's okay to forget the basics of scuba, like streamlining, proper weighting, spot-on bouyancy and trim, slow ascents and simple dive philosophies. I live (and dive) in an area that is very different from a recognized diving resort with pretty, calm, clear, and predictable waters. Ours here are inky black and often move with tremendous force. Both of today's tides are expected to be over 10' in differential, and some areas may have currents of 6 knots or more. Of course, my area is also famous for the Civil War, the Revolutionary War, the War of 1812, Native American culture, and fossils like megalodon teeth - one of the few places in the world where they can be retrieved. As such, local diving is very different than other places, with rewards that make the resort diver envious.
According to the concept of "technical diving," diving in 30' of black water in a lot of current, where you're not very likely to see your buddy at all, is "outside the realm of what's being taught" and therefore "technical." I do it nearly every day and can tell you that there's nothing "technical" about it. Despite what our local "around here" divers say, the basics still apply, and a mastery of them creates the easiest, safest, most fun, and in my case, lucrative dives.
There IS no dividing line between recreational and technical diving. The term was created by the "recreational" diving community to describe a diver doing dives that he was not taught to do. It was an excuse to explain why others were doing dives that they would not. It made them feel better about their own dives... And began to create an image in a "recreational" diver's mind that "technical" divers were big and bad and cool and had all of these neat toys to do dives that were extreme.
Well, this created a marketing angle for both manufacturers and agencies... They could list a specific piece of gear or class as "technical," and suddenly, everyone KNEW it was "bad ass" and "extreme" and everyone wanted a part of it. It remains that way today. The more it remains that way, however, the blurrier the line gets, because a manufacturer selling something "technical," or an agency offering classes as "technical" specifically negates the definition of "technical" - that is, it's now "taught" and no longer "beyond the limits of what is taught." It was the same way with "alternative" music in the '90's... The more it became the mainstream, the less it could be defined as "alternative."
Enter the term rec/tec... A term used to describe the blurry line. It's entertaining, isn't it?
The truth is, if you go up to any diver that can be clearly defined as "tech" and ask them if they're "tech," they will tell you no. Ask any diver diving a rebreather or any diver diving to 250' with multiple stages or any diver that is penetrating a cave or wreck or wearing doubles if they are "tech" and, unless they're involved in the industry marketing concept of "tech," they will tell you that they are not. Only the ones on the blurry line will answer yes.
...So if you ask a diver if he is "tech," and he says yes, by definition he's not. Yes, divers who dive every day and/or dive doubles, with stages, and outside the realm of what the mainstream agencies teach find it as funny as you do, and we're not above asking someone if they're "tech" just to be entertained.
A real "tech" diver will simply tell you that all water is the same - that as a whole, it's all connected. Sure, sometimes it's cold, sometimes it's deep, and sometimes it moves real fast. Sometimes it's salty and sometimes it's not. Sometimes it has inherent dangers in it... But the rules of diving all still apply, regardless of what special circumstances there are for any one particular dive... And every dive has it's own particular circumstances. The more dives you do, the more you realize the truth in that statement.
"Recreational" divers - those that only dive what they are told is okay for them to dive - can see this concept of "tech." Those divers on the blurry line consider themselves "tech" or "borderline tech." Those divers who really ARE "tech" look back on all of the dives they have done with 20/20 hindsight and realize that there is no such thing as "tech." They simply dive. All of the same rules apply as they did in the beginning of their diving, and only the mastery of the basic principles of diving - those that were covered in their Open Water and Advanced Open Water classes - will advance their dive skills. This concept is hardly "technical."
Oh, and for what it's worth, there is no such thing as a "tech" BC. "Technical" divers - that is, those who dive doubles or rebreathers (the most cited definition of "tech," as offered by "recreational" divers) - don't use BCs. They use backplates and wings. They have to - there are only three or four BCs on the market that even allow the attachment of doubles or rebreathers, and they fall dramatically short of the performance of a backplate and wing in terms of modularity, compatibility, and stability for doubles and rebreathers. The next time a dive shop tells you that a certain BC is "tech," ask if it can handle doubles or a rebreather. The answer will prove that the term "tech" is only a marketing slogan.
The best snow skiiers in the world aren't those that are able to do triple-endo-helicopter-flying leaps. They're the ones that, over time, have mastered the basics. Sure, they may be able to do monkey tricks, too, but it's the mastery of the basics that advance them into the Olympics and such.
Don't even get me started on "decompression" diving... ALL diving is "decompression" diving... When you go down, you compress. When you come up, you decompress. It's really that simple. The speed at which you can go down or come up does not define the term "decompression." To me, it'd be a bit like reserving only sports car driving to being called, "Acceleration Driving." ALL cars accelerate, just as all divers "decompress." The difference is the magnitude of acceleration or decompression, that's all... Achieved by a mastery and competency of the basics (in the car's case, power/weight ratio), not by some radical new class or BC deemed "technical." It also can't be nailed down to, "If you have a turbo, you're an Accelerated Driver" any more than "If you have a bottle of decompression gas, then you're a decompression (or "tech") diver.
Those that have crossed the "tech" line and look back realize that the line really isn't there. It's simply a matter of learning and applying what you've learned - progressively... And constantly moving forward in your diving.
The "tech" line - placed there by those on the "recreational" side of the proverbial fence - is a self-imposed limitation. Those on this side of the fence don't see a line. Or a fence, for that matter.