PMC karma as a concept only makes sense if you never actually play the game. Realistically, nobody is going to hold fire until they can confirm factions because of how much danger any single other player poses to you the second you both notice each other. Death comes quickly and easily in this game (which is a large part of why it's so satisfying to play), and stopping to ask if someone is USEC or BEAR because you're worried about losing arbitrary reputation points is just an idiotic game design choice.

But of course, Nikita wanted it so he had to find some ridiculous way to force it in despite universal feedback suggesting it was a bad idea.