The argument is that quarterbacks are not assigned win/loss record, because it makes no sense. Win's and losses are the result of planning on the part of the coaches, as execution on the part of the players. It is a team stat than can no more be attributed to a quarterback, than to the Denver Brocos's center, who set the route in motion at last year's superbowl.
I will concede that it is a talking point, but not an actual stat.