I personally don't believe that stereotype, even though my brother is a prime example of it (all he does is play Call of Duty)... It's probably just because this is the internet, and most people are jerks on the internet.
Honestly, I personally don't like those games, but it's because they aren't my thing. I just don't like guns. Some of my friends in school play those games, though, and they're perfectly normal (well, sort of) individuals. When it comes to the game consoles themselves, I don't have them, nor want them, simply because you cant play Zelda games on them. I have nothing against Sony or Microsoft, or the consoles, or the games. They simply aren't my thing.
I can't speak for everyone, though... Like I said, my brother IS that stereotype. And I have seen quite a few people on this site who believe that stereotype. From what I've seen most of it is because of personal experience. I really wouldn't know too much about their reasons, though.