Perhaps it's just me, but it seems that 95% of the time, the most rude and antagonistic posters are also anonymous - i.e. they are registered users, but their profile does not reveal their name (and usually, nothing at all about them). Does the fact that registered users are allowed to be completely anonymous embolden some percentage of them to routinely be argumentative, antagonistic and just plain obnoxious?

I think it does.

On the flip side, 95% of the posters who routinely post helpful, insightful, and thoughtful responses identify themselves by name in their profile.

The Moderators identify themselves by their real names - why shouldn't everyone else?