You see it a lot between iOS and Android camps. I get flak from Android fanboys constantly and I don't even use an iPhone. If each system was so perfect, there wouldn't be a need for anyone to prove anything. We're pitted into camps of imperfect systems in which each side is perfectly aware of their side's flaws but avoid the geek-sin of admitting they use something less than perfect by only pointing out everything wrong with the "other side" rather than admitting that everything is broken and telling Google and Apple about it instead.
I know one guy who used to actually reply saying, 'read what you just wrote, and feel bad about yourself.' One of the main problems though is that half the people on these forums are 10-18 year olds. I mean even Hacker News has a median age of only 25 (according to a recent poll), and it seems super-grown-up.