>>1954
Racism can be funny so it always was present on imageboards. There wasn't any ideology attached to it before /pol/ nazi infestation and spread.
For example now when someone calls you a kike they most likely honestly think you're a jew infiltrator. Back in the day when someone called you nigger it most likely wasn't because they thought you're being black on an anonymous japanese cartoon board.
It has gotten out of hand, as you yourself noticed, and there has been some countermovements against that already in Anonymous at large.