Or you have standards of discourse. I was on a moderated email list at one point that had extremely strict ones, including that anyone could call on you to produce primary sources for your assertions at any time. You could post further until you did so or you withdrew the assertion.

It also had forbidden topics, including religion and politics. Very specific topics that verged in those areas could be discussed, but general positions were simply not acceptable discourse on the list.

The list was pre-moderated, mind you: every message passed through a moderator before posting, and might be returned to you. It was extremely labor intensive and basically had a full time moderator.