I have been reflecting on ways to fix it lately. I was imagining something like reddit, but...
1) not completely anonymous / pseudonymous. Maybe a profile photo with you holding a sign with your username for verification (like certain subreddits do), first name, and SMS / phone number verification or something. That's all - not strong firstname / lastname identity like facebook, but also no throwaway accounts.
2) allow people to have a different alias for different subreddits, in a way that they stay separate and can't be easily linked. maybe that means one verification photo per subreddit, and all you really share across subreddits is your username / password. the thing of people looking through post history across different, unrelated subreddits and beating them up in response to their latest post is pretty toxic, and goes against real life where people tend to have a different persona in different contexts.