All you just did was point out that it would be a balanced system. You would only be abusing your self if you just ignore every other person. You would end up with a longer queue time to think about. It would deter everyone from doing just that.
I could be wrong here, but doesn't the Group Finder already do just this for PvE content? Block people from grouping with you on your ignore list. I don't see what the big difference would be.
You are allowed to keep bad / troll players out of your PvE experience but not PvP?