The fighting is a method of self policing. Keeps the game honest. You can't pull some dirty stuff and not expect to pay the price. Fisticuffs is a 5 minute penalty. It is not allowed at the youth levels or NCAA levels. 3-5 game suspensions are the norm. Minor Pro and American/Canadian Junior/Minor Pro and NHL run the same rules. Refs are instructed to separate the fighters when 1 is exhausted or is in a hopeless position or in the event of a clear knock down/knock out. The is inherent to the hockey culture and goes back to the beginnings of the game.