Not a hockey fan either, but I’ve often asked this question of my friends that are. They all same the same thing: The fans enjoy and expect it. To me, it’s dumb. One team ends up a player (or two) down, and that’s when a lot fo the scoring happens. Ergo, you fight and you are more likely to lose. Pretty much any other sport in the world and you’re off the field of play, and often for a long period of time.