I prefer a looser type of diving. I live 5 minutes from a good ocean dive site. If I get off work early and the ocean is flat I, go diving. I'm not going to stay out of the water because I don't have a buddy.
I don't like the math, how many DIR divers do you need in the water if one is a spearfisher, how many divers do you need in the water if you have two spearfishers.
I like my snorkel on my mask for those long beach swims in a chop, if I put it in my belt while I'm submerged, I'll lose it.
I dive a steel tank in a T shirt.
I have no inclination to go deep or in caves.
I've been diving for 35 years and haven't had a use for it.
That being said, look at the WKPP project and their incredible accomplishments. How many divers died doing those extreme dives. They must be doing something right. It wasn't Moses passing down the DIR commandments. It was a bunch of people screwing up, oops-that didn't work, almost killed me, won't do that again-and learning from it.