I don't know why people let their ego get them better of them. But more than focusing on a team or a 'console' (same thing), I think those are just the excuse. A symptom of the main problem. I think the more ingrained problem is anytime they feel their views or opinions are being threatened, they have to throw up a wall. Whether its an immediate contradictory opinion or a negative statement (such as a veiled insult) or some way of covering up the fact that they aren't in control of either the conversation or their own emotions.
And I'm not going to say its entirely their fault or heck, that I'm not guilty. If you've been on a forum and posted anything beyond COMPLETELY positive posts, you have done it too. But there's degrees to it and you may not be recognizing your actions.
While I doubt people are going to change their ways, I do think the way to change it is simply for everyone to just, as stupid as it sounds, think about what they say and ask yourself if you would want someone to say that to you. If you're about to tell someone a veiled insult or a LONG speech about how 'X' platform/game sucks, just recognize how you would feel listening to it on the other end. Cuz you WILL be hearing the other end of it soon.