To me there is a difference between "shouldering" and bringing the opposing forward down by pulling his shirt or using your hand to stop his progress.
If you have watched South American football, you will see their incredible footwork, ball control and selling a dummy to the opponents.
All these skills fail when the opponent simply uses his size and weight to stop the player, instead of trying to take the ball away from him.
I watched the 1986 World Cup match between Argentina and S.Korea. Maradona was unstoppable. Time and time again the opposing players stopped him by kicking his leg from under him. One had to give credit to Maradona for not reacting even once to the brutal tactics. The referees allowed the South Koreans, maximum latitude to play this kind of game. I think it was after this cup that FIFA became stricter regarding foul play.
