The infighting between fandom message boards and forums is my pick. It hasn't stopped, it just keeps going. Years ago I frequented a Resident Evil message board, and while things were mostly under control every now and then you'd get topics popping up about how a different Resi board was full of spammers and flammers, and it was the worst, or this other board was so strict they were banning people left and right, and this place is better, no that place is better. And since I haven't been around message boards much in quite a while I thought it stopped until I realized the crap being spewed about Youtube comments and 4Chan, Reddit, is all the same thing. It's not so much that it's heated, it's not so much that fighting is that intense, because it's not, it's that it doesn't go away, that so many people are involved in it, and that it seems to have come to be normal and accepted.