Same reason they are allowed to sell nerf bats for children. It looks violent, but in reality is essentially harmless. Two guys trying to keep steady on ice while grabbing onto each other’s jerseys have no leverage. They’re both wearing mouthguards and helmets and as soon as they fall to the ice where leverage IS possible the refs stop that shit immediately.
You ever see either of the 2 ‘combatants’ get examined by a medic, let alone rushed to the hospital, after a fight? No. They go right to the box for 5 minutes to cool down because all they did was tire each other out. Hockey players have to deal with far more violent events dozens of times a period in normal play.
Boxing and Pro Wrestling are far better targets for people against this. It is literally a sport about fighting. Ban martial arts competitions too while you’re at it. 2 guys flailing on ice to rile up their teammates is small fry.
Same reason nerf bats are allowed.