There's always an US vs THEM element to any culture, but to me it seems like there's been a relatively recent social trend (as in like the last decade) that anybody who isn't jumping up and down waving pompoms for the one right side of an issue is presumed to be an extremist for the polar opposite wrong side, and all their other views about the world and their overall way of life are probably also despicable. It's very simple binary thinking and works well with memes - minimal information to take in, quick and easy to process, one obvious right answer. It also fits gaming mindset very well - is this NPC on my side or should I kill him?