MGibster
Legend
This is probably my least favorite part of any fandom/nerd-community.
My theory is that when people become part of a fandom, or as you put it nerd-community, it's part of their core identity. And anything associated with that fandom will have a much deeper significance to those people than simply being something they enjoy. When Firefly was still on the air, I had several friends who really, really got into it and I couldn't have a conversation with any of these people for very long before the conversation steered towards Firefly and it was bloody annoying. It was a big part of their lives and they networked with other "Browncoats," as the fans referred to themselves, and actually built a lot of social connections they still have to this day.
And this is different from people who simply like a show, book, game, or whatever. When something is tied up in our identities, we tend to defend it when aspects are criticized. I thought myself immune to such things, but as a graduate student I remember getting into a discussion with an Englishman where he asserted that colonist had no justification for their little rebellion, which, as an American, kind of struck a nerve.
Pictured below: Two graduate students discussing the finer points of the Stamp Act and the legitimacy of the British Parliament to govern the American colonies.