A studs up sliding tackle is at the very least a cautionable offense at every level of soccer, including professional, except, apparently in the girls high school game in SC.
There is a difference between tough, physical soccer and dangerous soccer. It is the referee's job to enforce the rules and, as much as he or she can, protect the players. If you don't understand that, you have never taken the referee's course. If the referees do not have an influence on the game, if only the players have anything to do with the game, then why bother having refs?
And if coaches allow or encourage violent play, some players on that team will play that way. If a player who slides studs up is immediately removed from a game, she will learn to slide properly or keep her feet.