In my world there would be entry bars. It's not only about the safety of the unfit it's about the safety of the people who are instabuddied with them or have to go rescue them. If you can't swim you shouldn't be diving.
I'm not saying I necessarily disagree with that entirely. I am saying that being able to swim without any aide and swimming with a wet suit on are two different things. I am also suggesting that some onus must be placed on the diver to dive within their own limitations.
Helping people improve their swimming technique makes them better divers, helps them understand breath control and gives them more overall confidence in the water.
No one is yet talking about offering swim coaching. Rather, it has been all about a pass-fail test to bar entry to diving. There's a heck of a difference between helping people do something and testing if they can meet some arbitrary bar.
The grossly unfit should be bowling, not diving.
Isn't the point of a medical clearance to put the responsibility of determining fitness onto a medical professional who (theoretically) has the appropriate expertise to make such a determination, rather than placing it on a dive instructor who does not necessarily have the ability to do so.
A 60 year old 300# man who can barely swim may be able to go 600 yards and, while being very out of breath, could complete it due primarily to being positively buoyant. While a 180# guy built of nothing but muscle might be hard pressed to swim at all due to being naturally very negative.
Or, our hypothetical 300# fellow may be in far superior diving shape than our young 180# guy with great muscle tone but who has a PFO and arrhythmia. even if the 300#'er can't swim very far at all, and the 180#'er does it in record time.
Divers typically are in the water with flotation - a BCD and a wet or dry suit. Swimming with flotation is decidedly different than swimming with out. One of my diving mentors is a guy who is in fantastic shape. He is pretty much all muscle. He is naturally negatively buoyant. He sinks like a rock and has a very hard time swimming even short distances because of that. But he is an excellent diver, and in a wet suit he can out swim me all day long -- even though I swim a mile or more every day and he does not.