Every forum needs a sheriff or some other mechanism to limit damage and to encourage engagement.

The general rule of conduct has to be that everyone needs to separate the speaker from the speech. Nothing wrong with contesting facts as long as it is done in a civil tone and in pursuit of more complete knowledge and better understanding.

Personalities. Long before an abusive poster clearly and obviously violates the rules it is often clear they are malicious. If they are not removed, reformed or otherwise checked they drive away exactly the sorts of people a forum wants to hear from. People who are driven off or deterred from posting because they wish to avoid the undeserved abuse that might be leveled at them if they post.

If it isn't done you end up with petty tyrants who homestead the forum and make it their their private balcony for regular rants and leveling of abuse toward anyone who fails to agree with them or show sufficient deference. Or punks who get their jollies traumatizing people and vandalizing a community. Sometimes a bit of both.

Someone has to actively maintain a safe middle ground where people are free, even encouraged, to post and state what they feel in a civil manner without fear of abuse.

I'm glad this forum has one. Good job.