==this isn't directed only at you, Mike, but your post gives me a nice little soap box to start with==
And some won't. This kind of talk is like pointing at the worst drivers on the road and drawing all kinds of conclusions about the rest .....
Some people are just heads-drilled-full-of-holes idiots and unfortunately some of them become scuba instructors. Most are not like that and to conclude that they are because the system doesn't do a good enough job of screening the losers is drawing bigger conclusions than I believe can be supported by the big picture.
In other words, while I will agree that the system doesn't do a good enough job of screening the losers but that doesn't make the losers the norm.
There is also another aspect to this that I believe is often forgotten, which is personal responsibility. If someone is taught badly then they should be able to recognise that (at some point) and should take responsibility (regardless of what happened to get them in that situation) for doing something about it.
And finally, where you set the bar is important. It's literally impossible to teach flawless buoyancy control to everyone. At some level, personal aptitude plays a roll. Some people can learn it with a few hours of instruction, some will still be struggling with it after 50. Just to give you an example, I once had two people in the pool for a scuba review. They had done all of their training together and all of their dives together to date. One of them was totally sorted out. Alert, accurate, skills nailed, buoyancy good, finning good...etc and the other one could do *nothing* but look at me like a stunned cow the whole time. This case was extreme becuase I don't believe the diver in question should have been certified but such variations, even in a single group of people taking OW are the norm. At some point you need to set a limit on the effort you're willing to put into to and let people just go dive (assuming, of course, that they've learned the required skills).
{edit- added} BTW, this is both a fundamental difference and a fundamental similarity with DIR-F. DIR-F doesn't attract as many "stunned cows" as PADI OW does (that's the difference) and they also limit their effort and let people just go dive (the similarity).
I just think that expecting OW students to be able to roll straight on through to DIR-F or Tech-1 is absurd and bashing PADI and others for not making that their priority is also absurd.
R..