I really think it's sad to try to take away any expression of joy in achievement for young players, especially in an environment as emotionally charged as a hard-fought soccer match where one goal can change the course of the game. There is a need to regulate types of celebration that are directed at taunting the other team, yes...but to card a player for a moment of celebration with his own sideline just seems to take the joy out of it. Emotion and crowd involvement are often big factors in the momentum of a game, and to smack a team or player down just for getting "up" can have just the opposite effect.
Back in the days when I first started coaching, we were told "make sure your celebration is back on your own side of the field." Seems fair enough to me.
