I don’t want this, but an easy answer is to eliminate anonymity on those forums you want to be less-toxic. A hard answer is to maintain a community properly to

I don’t want this, but an easy answer is to eliminate anonymity on those forums you want to be less-toxic. A hard answer is to maintain a community properly to ensure self-policing with good backup moderation, like they do here at HN. There are only two (?) moderators but the culture here is very well maintained to self police threads.