"There was a nasty kind of argument that used to happen, where people would literally try to score points off one another, and users voting on the thread became

"There was a nasty kind of argument that used to happen, where people would literally try to score points off one another, and users voting on the thread became like a mob egging on two people fighting." This problem arises from two features: comment scores and arbitrarily deeply nested threads. Considering how valuable comment scores are, it seems worth trying to remove the other feature instead. (Perhaps by preventing replies until after a delay, which increases with the depth of the thread.)