That is a misconception. Things can go bad very quickly in 90' of water. Very few training agencies spend the time necessary to train a new diver in emergency procedures and recreational dive gear is not well designed to safely and comfortably allow 2 divers on one air source to surface, while performing safety stops and controlling the OOA diver.
I would be so bold as to say that 99% of all new divers could not handle and OOA emergency of their buddy safely in 90'. There is no muscle memory.
The only reason we dont see more fatalities in diving is a testament to how good dive gear today really is and how very few failures there are. Also, most diving is done so shallow that OOA emergencies pretty much solve themselves, by the time they fart around their poor buoyancy skills have floated them to the surface already.
I don't know the statistics but have first person account from my husband on a charter boat with an insta-buddy. A young guy in his 20's, run out of air, quickly swam to my husband and just stare a him with huge eyes, my husband only had 1 second stage so without letting go of it, placed it in the kid's mouth and after a few breaths took it back. At the beginning the guy didn't just easily let go the 2nd stage, but after a couple of back-n-forth my husband commented by the time they reached the surface that guy probably could have written a thesis on the art of buddy breathing even if he was taught to use an additional 2nd stage.
There may not be muscle memory but there's usually a strong survival instinct. If you don't know what to do when your buddy runs out of air, most likely he'll figure it out if he can get close enough to you and grab your second stage.... or he'll become an statistic.
Available air is not a secret by the way, you just need to look. Honestly for the life of me I don't understand how some people run out of air. Yeah I hear about gear failure, but truly not quite buy it. After 4 decades diving all kinds of gear I've always managed to end my dives with some air in the tank, used to push it when I was younger.. but the more I pushed the more I was paying attention. Like when you speed in the highway and have your head in a swivel looking for LEO's
As far as fewer diver death being a testament of good gear, I'm not sure that's a direct cause-effect.
My thought is that recreational diving is just not that difficult, if it was you wouldn't have so many weekend warriors involved in tech dives, they would get their adrenalin from regular rec dives. Going 100' to see pretty fish or some ship that failed is not that big of a challenge once you follow the few very basic rules for not getting yourself kill. Tech divers go further and further because they want more and more challenge.
Recreational divers should become self reliant because it would enhance their experience and it is not that hard. Rec divers that give a dam can do it without depending on 10 tons of gear. Everyone should be able to dive solo, whether they choose to share their dive with others or not.
Why does it have to be buddy or solo? Why not both?