Insults, flaming, threats, offensive language, etc are most times edited away, or the individual post removed.
When the post has a majority of posts in it that are offensive, or simply a back an forth of trading insults and vitriol the thread is closed...
Where a post is viewed as being solely for bait, or has degenerated too much it is removed.
In some instances theyre discussed, and in all of these cases it is an imperfect system. some posts are overlooked, some may be felt to have been too heavy handed, and so forth.
as SW says often, there are only so many mods to go around.
You are welcome to submit yourself for consideration to become a mod...send SW a message.
you seem to have a handle of what is or is not censorship. give it a go...
I see that many complain.... but rarely if ever does anyone so doing step up and try it from the other side...