It's not? Heh. It definitely is defined by "breaking the rules." Pick up a dictionary. When put in the context of football it's necessary, I think, to take intent into account as well. People get handed cards often out of sheer clumsiness; them being penalized doesn't make them cheaters.
They are penalized because they broke the rules. Some do so willfully, some accidentally. Sometimes there are smart fouls to give. That would be considered cheating in your definition. When Marchisio brought down Pandev on a break against Napoli a couple weeks ago, earning him a yellow, that defines him as a cheater in your book.
Even a player who tears off his jersey after scoring a goal... it's against the rules, he willingly knows it, and he gets a yellow card. That, by your definition, also makes that player a cheater. Sure he may not play an "advantage" in that situation. But who's to say the goal celebration isn't partly an intimidation factor? Or riling up the fans so that they give the home team more energy?
It's absurd.