On your point about practicality. I think a big point about not breaking up fights is that they are on ice, which is slippery, and they won't have a good grip on the ground, and on skates so not the most solid footing. I'm not saying it's impossible, I'm just saying it's not a worthwhile risk when both hockey players have full gear vs. a ref with minimal gear.
Plus, the context of it being accepted as part of tradition weighs on why it's not as heavily regulated. If they wanted to, officials can force teams to be disqualified or ban players. Another point is It is more profitable to allow fights. Unless players themselves argue to ban fights for their safety, this will likely stay legal. The fact is, the new meta of having a good team but able to rough up the opposing team is better than it was before. Also quite a bit more enjoyable too.