The problem is that I find lies, threats, and abuse to be objectionable, yet most here seem to see no problem with them as long as they are directed at one's opponents.

Personally I find it much more objectionable when someone who is arguing from the same direction as me starts mouthing off in that kind of way. When someone in the other corner, so to speak, does it, there's a sense in which I recognise it as a self-inflicted wound.

I'd much rather not see it happening at all, because it messes up discussions, and I value good discussions, but if anybody is going to do it, I'd rather it was an adversary.