Moderation is hard because designing communities around effective moderation is at odds with the growth and monetization goals of the major social media companies. The problem's tractable, just not while operating something that looks like Facebook or Twitter. They have to expose everyone to posts from as may people as possible as much as they can get away with it, to drive "engagement" and growth and feed their ML. Tighten up post visibility so it's not like one big free-for-all and suddenly things get much easier.