Why are each of your lines wrapped in ellipsis?

…what many anti-fifth-edition positions miss is that it’s not about learning a new system, it’s about compatibility across a vast ecosystem of disparate settings and campaigns…

I don't think 5e is especially compatible with disparate settings and campaigns. It's not an actually generic system like Fate or GURPS. It's got underbaked or entirely missing whole RPG subsystems and mechanics (eg: social conflict, succeed-at-a-cost, metagame currency). It's highly opinionated in other regards- hit points, class and level, resting. You can hammer the peg into the hole, but you could do that with anything.

It's not a good system for modeling anything outside heroic fantasy.

It's certainly a popular system, but many things are popular without being good. But, if your top priority is going where people are, by all means stick to D&D 5e, reddit, facebook, etc.