The OP is asking why negativity dominates in more open communities. Um, because you're admitting more diversity? When you don't limit yourself to socializing in a self-selected chatroom or friends group, you hear about the things that matter from a range of people. It's not exactly a secret that there's turmoil.

Does this really have to be so academic? I'm sure there is something scientific to be said about it. But on the other hand, maybe you shouldn't insulate yourself in a world of rainbows and sunshine?