I agree that much of today's diver training is poor. Standards for Diver's and Instructors are at an all time low. I also agree with you that "of today's trained and certified OW divers, a very large number could not survive by themselves in a swimming pool for several hours without help." What's also unfortunate, is that many of today's current Instructors have yet to recognize that this poses a safety problem at all and some even quote statistics that the Diver fatality rate isn't increasing, so everything is fine.
What you may be missing is any Diver who seeks 'technical training,' is not dealing with the typical Instructor or "high volume operations that employ Instructors that are poor divers themselves." I certainly can't speak on behalf of all Technical Instructors, but I'm a hardliner when it comes to any type of Diver training (OW through Technical Instructor). I'll work with the student for years if I have to, but Standards have to be met before they get the card. The card is well earned before I'm through.
Jim and I discussed this recently. We both agree that we don't certify anyone to dive unless we feel comfortable in them diving with a member of our family. This use to be the standard that was applied by most Instructors, but today it's a relic of a by-gone era (like me). That doesn't mean that we don't have it right; it's just not a profitable attitude to have in today's Society (where many people seek instant gratification)...
Agreed, but almost everyone can be trained properly and proper training should be available through a Technical Instructor.
Personally, I only dive air under 250 FSW. If Helium is available, I prefer to use it. Unfortunately, it hasn't been available in every place I've wanted to do a deeper technical dive. At such times, I use air. In my early days, Helium was seldom available at all job sites, so I didn't have a lot of choice. After I became more experienced with air at depth, it didn't present the same concern as it once had.
I don't believe that surface supply "addresses the most severe problem of the poorly trained diver" at all. The training it takes to use SS, is much greater than if the diver was trained to use SCUBA properly. Poorly trained divers shouldn't be diving at all (in my opinion).
I was the Diving Operations Officer (Navy) at DCIEM (in the 70's and 80's) and was involved in testing numerous subjects regarding narcosis. I coincidentally did my Masters thesis (Hyperbaric Physiology) in-part on N2O narcosis (affect on ventilation during resistive breathing). Most people will show measurable changes in problem solving skills in as little as 50 FSW. There are some degrees of variance in how narcosis affects people (perhaps similar to some medications) and how it will affect the same person in different ways at different times.
The important thing to remember, is not how narcosis will affect you (it will), rather than the amount you allow it to before it becomes an unnecessary hazard. If you are being notably affected, you scrub the dive. Some days I wont dive below 150 FSW on air and at other times I'm fine at 225 FSW; 200' usually doesn't present a problem for me. Sometimes I have a problem with my ears and I scrub the dive at 20 FSW. Again, it's all about knowing what to do and what not to do. Proper training makes the difference.
I suppose I take exception to anyone saying: It's crazy to dive deep-air when there's another gas; It's crazy to dive in a Cave or a Wreck when you don't have to; It's crazy to use a CCR because they are dangerous; It's crazy to dive at all because the Sharks will get you... Deep-Air, Cave, Wreck, or even Diving at all, can be safe or unsafe. They each have a degree of risk. The only thing that's important is to do it responsibly and choose the level of risk that's acceptable to you. To best evaluate this, get educated about the facts and then you're in a position to make your decision...