Staying off topic for a moment... I bet there's an interesting study in this. Something along the lines of neurochemical or psychological rewards when one does something like "downvote" in self-regulating forum like this; seems like it would be narrowly focused enough an as compared to say, trolling, that you might be able discern something in from that sort of behavior. (I'm clearly no scientist :-) )
For the record I agree with you. I think when someone says something that is silly, naive, or somehow just wrong in a forum like this... it seems like it would be far more productive to both participants and observers to have someone just point out what's wrong (yes, that takes time, but you cared enough to down vote, right?) Some part of the time you'll just uncover a misunderstanding or actually find out the person that would otherwise be down voted may have had a point.
