The fundamental problem here is that people discover things that make them angry. Platforms need to figure out how to prevent that, how to let open-minded people discover others who think differently, while keeping crybullies in a comfortable bubble.

For reddit, part of the problem is that everyone who isn't logged in sees the same frontpage, which means they see posts from these controversial subreddits and get angry. They should make it possible to subscribe to or block subreddits without making an account.