I'm sorry, but in my experience in multiple forums there are some people that truly are morons or idiots. If we can't let them know what they are then there should also be a no dumbf***ery(not sure about how good the swear filter is on this site yet) allowed rule.
I'm not talking about stupid questions here, because what we may take as common knowledge other people may not have a clue about. I'm talking about people who run around making stupid posts and generally not having a clue about what they are talking about. My favorite saying is, "When in doubt, shut up."