I don't want to put any judgement here, so I'll share my experience from moderating one forum which I don't want to mention here.
I used to be a moderator on a relatively popular forum. It was quite offensive and personal from the beginning, but it was a small community, people used to know each other, so that was an acceptable situation. Sort of a "friendly" unfriendly place. Then the forum became popular, many new people joined, newcomers adopted the culture they way they saw it. The result was/is quite a few users who have no respect whatsoever, personal insults, lots of drama, etc. A few people develop anxiety and other issues, which made them perfect targets for other trolls. The forum became a very toxic, although I'd say it's only 5 or 10% of people were responsible for the majority troubles. Same drama queens again and again.
I observed how people behavior changed over years. Quite a few people became impossible to communicate, they became very offensive yet very sensitive, and with enormous ego. They really got troubles with communicating other people in a calm and constructive way. I'd say they needed a help of psychologist. Worse yet, this culture went far out of the forum. Many members brought the same culture and same problems to other places too.
I attribute this to the way the community was managed. One of the rules was is a user seems to be a valuable contributor, s/he could do everything. This policy re-enforced certain behavior among people.
I believe mutual respect is far more important in the long run than anything else. My advice would be to just erase offensive messages, this worked quite well on our forum. Trouble is, we were not able to find an agreement what was offensive, and was not, part because users learned how to write offensive messages in a way that it's hard to judge if it's offensive or not. So, moderators were too busy discussing these matters instead of doing anything. Unfortunately, some people became very skilled at ruining communities so it's hard to see what damage they cause until too late. Offensive behavior is also "contagious", I saw normal users turning into trolls.