People have always grouped together into communities with extremist views in the physical world. And I am not even talking about fringe elements. Many sects of all major religions for thousands of years have thought the entire outgroup is going to hell.

The problem with social media is not that. It is the feed algorithms that make expressing any extremist position the only way to get other people to talk to you. Fix this problem and many of the problems will go away.

Unfortunately, as it is a social coordination problem, the only way for this to happen is government regulation that either bans feed algorithms altogether, or ensures that users individually have full control over the algorithm for their own feed.