Generally any unpleasantness and lack of civility needs to be moderated out in some extent, or the platform gets completely taken over by trolls and normal people leave. That’s just the end result. Anyone who’s been involved in online communities know this.
I see this in subreddits. The subreddit of my own country is poorly moderated and virulent in trolling and insults. But you look at something like AskHistorians and you see academic level content. NeutralPolitics is the only politics subreddit that isnt instantly toxic. Why? Moderation and rules.
It’s astonishing how far you can move the content with moderation.
A rule I’ve learnt recently and really loved is - every community can be judged quickly by how comfortable women are in it. The first sign of lack of moderation is male sexual harassment - because that’s the first thing male assholes do. You have to deal with the assholes. Assholes exist and are relatively common. If you allow assholes, women leave, and when women leave, you can tell something went wrong.