Everyone's a dick inside. The Internet is just a way for the vast majority of people to release their inner dick in the [almost*] full knowledge that they won't face reprisals for their actions or words. Ever hear of GIFT? It's real, even official academic studies agree with its existence.
*- Unless you piss off someone who happens to be a computer genius on 4chan or SomethingAwful...then your life becomes hell.
On the topic of shipping, it's fucking stupid. Reading threads about XY couple or how X should be with Z instead of Y or whatever reads like a conversation from third grade. And some peoples' posts/reactions...it no longer surprises me that it's just as likely full grown adults as kids to be spewing some of the vitriol that one sees.