Even considering the fact that some might use it as a venting/coping-mechanism, I still have a hard time understanding the need to slag off on schools or act like a toddler.
I hope that's the case. I'm not too sure though. I think there are those who expect to gain admission to every school which they have applied to.
I sincerely wish for everyone to get in somewhere where they'll be happy. It might not be your "dream"-school, but if you end up in a good environment with supportive faculty and a good cohort, it'll be as pleasant of an experience as it can be.