It's not the complete answer, but a big step in the right direction is deplatforming bigots and abusers. We know this is effective in limiting their reach and the damage they can cause.
The question you have to ask is why there is so much resistance to implementing a strategy that would make everyone's day to day online experience better.
You have to ask why these places don't want to be better.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!