Without comment on them the moderators are charged with enforcing the rules.. For example I moderated in a medical forum. I was charged with, amont other things, making sure that any Teens were not posting seeking... Older companions shall we say.. (never happened but watching for it was part of my job)
One of the rules is No Name Calling/flaming.. And often some discussions devolve into just that
"Why you stupid _____ if you can not see that ______ you must be blind ______."
And when that hapens the door is locked.