As a person who has had their fingers cracked a few times, I think they balance the freedom of the members to express their opinions, and the civility of the forum. You may not all see the PM behind the scenes, but I like the fact that they will send a private message and ask for some understanding or call for an end of something going bad.
Moderators on other sites make it public, puff out their chests, and make thing far worse than it ever needs to be.
I think the only thing worse than bad moderators, are folks who come to forums and expect to never see a debate, then are the first to claim someone is starting a pissin match when only a heated debate is happening, which is to be expected at times from passionate people with varying opinions.