Yeah, NXS, that's fine in games that winning means EVERYTHING and they have rules only looking towards that goal, like oh, what do you know CHESS! Or other table-tops, or fighting games. Or war (although, what do you know for a second time, even war can have some who follow internation rules and those who don't and commit even greater atrocities).
You know what the point is in chess or similar games? The rules are clear and set. There can be no differentiation between which ones to use and which ones not to. Each player should use all of them.
If you go ahead and punch someone while playing chess, than scatter three of his pieces, including his king, you can say that you won.
Or if I get a handgun and shoot you in the head, I win no matter what we play!
RPGs use PK and mechanics and the system as a tool, not as their main focus or as the ends. They are the means.