[chimpinee]

Asking somebody not to be mean seems reasonable but he only gets mean after he has already "lost it". He then unfailingly perceives the other guy as the mean one and himself as the victim. If he had the self-awareness necessary to monitor his emotional state then he would not become mean in the first place.

Combine this with the fact that most people come to news sites for validation rather than enlightenment and one can expect mean comments to grow in proportion to the popularity of the site