Note: I am speaking strictly in the context of recreational sport diving.
You table proponents haven't mentioned Nitrox. How does it work out for you to memorize all that table data when you go somewhere to dive Nitrox? Or is Nitrox too new-fangled for you, too? Do you have the Nitrox I and Nitrox II tables memorized also (i.e. EAN32 and EAN36)? What if you go to NC to dive, where they bank EAN30? Or do you just have the EAD table memorized, so you can convert and calculate using the memorized Air table? And what about if you dive on EAN32 for your first dive and then EAN36 for your second?
I think the only value in teaching tables is IF they are taught in a way that builds a picture in the student's mind of how depth and time affects inert gas build-up and off-gassing, and how to do a rudimentary sanity check of of NDL. But, I think that a lot of people teach tables in a way that does not do that at all. They are only really teaching the mechanical process, so that the student can get the right answer on an exam. Further, I think there are more effective ways to impart students with a sufficient understanding of on- and off-gassing and how to sanity check an NDL.
The OP compared recreational diving and use of tables to military and commercial. I will, instead, compare sport divers to technical divers. Sport divers have computers and don't need tables. Advanced technical divers almost ALL do all their diving without tables. Tech divers generally use something like Multi-Deco (or similar) to plan dives. If the most novice divers don't need tables and the most advanced divers don't need them, then what really is the point?
So, I will go further out on the limb than what I've read in this thread, so far, and say that I, personally, am in favor of expressly removing the teaching of tables from OW curriculum. As in, change the standards so that OW instructors are not allowed to teach tables.
Why?
Well, as I said, I don't see any value in teaching them. And, I also feel like there are some specific hazards related to teaching them.
I have seen several people (recreational sport divers), in real life, talking about planning a dive using tables where my observation was that they were or would be doing it wrong. One example: "Well, on my last dive I dipped to 90' for a few seconds, but my average depth was probably about 70'" and then proceeding on to use tables based on a first dive of 70', instead of 90'.
I have witnessed an OW instructor teaching tables to an OW class and teaching it incorrectly. And I mean, very wrong. During the instruction, the instructor got to planning the 3rd dive and was getting answers that finally became obvious that they were wrong. But, the instructor was so rusty on use of tables that he didn't figure out where he went wrong. And, since "nobody actually dives tables" anymore, he just brushed it off and moved on.
The point of all that is that I think teaching tables (NOWADAYS) results (MOSTLY) in producing divers who would never even try to plan a dive using tables, a very few who would actually plan dives correctly using tables, and some who are essentially ticking time bombs. They think they know how to plan a dive using tables - and they are wrong. And, if the right circumstances presented themselves (potentially, years after their last real exposure to planning using tables), those divers would (try to) plan a dive using tables, thinking they were doing it correctly when they were not, and potentially hurt themselves. Further, the reason they do it wrong could be because they are rusty and just don't remember it correctly. It may have been years since they were taught tables and they've never looked at them since. Or, it could be that they were taught incorrectly in the first place.
Staking your health and safety on a tool that has been sitting, getting rusty, for years is not smart. KNOWING that the tool WILL sit and get rusty, why give it to them in the first place? Better to leave them in a position of having to just sit out the rest of the day. I liken teaching tables to people who buy a gun, take it to the range and shoot it a few times when they first get it, then carrying it around for personal protection and never again go to the range to practice.
Yes, there are people who are an exception to this. I learned tables by reading the PADI Open Water manual back in the late '80s, when I was dating a girl who had recently gotten certified. I didn't get certified myself until 2014, but I could still remember how and use tables to do the planning for an initial and repetitive dive. But, what I've seen out in the world is that the vast majority of recreational sport divers are not like that. For the ones that are, they can pretty easily get tables (from online, even) and work out how to use them on their own, if they want. But, really, who would want to?
For the rest of the world, OW class should make sure they understand the basics of what is happening to the gas in their bodies as they go down/stay down/ascend/off-gas on the surface. They should learn enough to sanity check an NDL. The Rule of 120 (or pick your happy number) may be sufficient. Learn the rules of computer use (e.g. Do not change to another computer after you have already done a dive. If you only have 1 computer and it dies during your dive, sit out the rest of the day.) No need to learn tables.
Buy a computer. Better yet, buy two computers. They are cheap nowadays. Learn how to use them. Always dive with your computer(s). Never need to use tables.
