Why? Because we're human. I too have been gaming a long time, since the Atari era. Online gaming has really only come to fruition in the latter half of that, where competition between people greatly increased. A lot of people need the feeling of being better than others. What we do in real life also affects that, from what we drive to what we wear to what we eat. Don't even bring up religion. So I think a lot of this has transferred to the virtual world. Everyone wants to feel special in their own way and anyone who challenges that will take offense to that. Online gaming has also brought the entire world to one place and interacting with other cultures will create tension. As one may think what they say or do is fine, the other may take offense to it, creating a snowball effect.

Labels exist everywhere, like it or not. Whether it be out in the open or what people just think about you, its human nature. We are not all the same person, would be pretty bad if we were. We are not robots we have free will and thinking, deep thinking. It actually baffles people how our brain function differs so much from the animal world (aliens). Put a diverse group of people into the same room together and see what happens. People will eventually break up into groups of like minded and start making labels or talking about the other groups. Online gaming is just a really big room.