Reddit tackled that by allowing communities to self moderate while providing a baseline of what's platform wide acceptable.

Although there are many crappy communities, no other social platform comes even close to Reddit's best, well moderated subs.

I believe social platforms keep failing exactly because they try to solve spam, etc.. globally and that's not possible. It's better to empower mods community builders.

I also believe there is a good opportunity for a social platform that allows mods and builders to be paid somehow.

Edit: Another though - that's also how Discord took off.