one of the best communities I have been part of is heavily moderated
They often are as a space can be created to facilitate purpose and action. Universities used to be places with open discussion, now they are places where anything that might offend anyone is closed for discussion. "How's the weather?"
Now I can't comment on what is going on at universities. Over here, I've generally picked up on dissent towards "trigger warnings", which have been translated as "we cannot talk about" where they really are "here is a thing that we are going to talk about" - i.e. a useful thing for PTSD experiencing individuals.
But, for the gaming community, the closely adhered to moderation cut out the toxicity and replaced it with actual proper discourse. Naturally, one size doesn't fit all. You can't slap down a rule for all, and that makes things hard work.