Back in the day when there was only one referee who was often distracted and there were cheap shots dished out behind the play, maybe there was a need for fighting in hockey, for players to police themselves. Nowadays with cameras catching everything on the ice, that need no longer exists. What has to happen is that the league take cleaning up the game seriously, enact penalties during the game or after the fact on video review for slashes, slew foots, crosschecks, any hits to the head, etc. It sounds crazy now but that's the way the game should head, and it's infinitely more sustainable than what happens now.
The idea that fighters keep the game clean is now a disproven trope. Bigger, meaner players, now two or three aside on some teams, with no hockey talent or value to their team aside from their intimidation capacity, cruise around the ice five minutes a game and cause mayhem, trying to justify their spot on the roster. Designated punchers face off and neutralize each other at best. The Chris Prongers and Milan Lucics of the game avoid these players but use their size and strength advantage to crosschek and elbow smaller players. Ryan Kesler slashes with abandon, but tells an opponent trying to avenge a transgression that he "doesn't fight fourth-liners". On and on it goes, the fights don't settle scores, they're assymmetrical and just create more anger and blood-feuds, our own version of the Middle East peace progress on ice. Did the Detroit Red Wings settle their score with Claude Lemieux, or did they escalate an incident into a much longer, bloodier ordeal?
We have to understand that the idea that a fight allows players to release their anger and return to a normal, even state of operations is based on the fallacious 'Drive Theory', which held that man was a creature who accumulated needs like hunger or thirst and had a drive to reduce these needs. Once you drank or ate, you returned to a normal balanced state, which was healthy. Same with anger or frustrations, these built up and if you didn't do anything about it you'd blow, it was healthy to release it now and then. That theory has been disproved, its central tenets debunked.
Specifically when it comes to anger, a person who 'vents' their anger once in while isn't healthier than the person who doesn't, and isn't dealing with frustration in the only way possible. In fact, people who act out on their anger don't release stress, as is regularly depicted in popular culture, what they're actually doing is learning to be angry, setting up a pattern in behaviour that is repeated and escalated, so an angry profane outburst becomes smashed furniture and a hole punched into the wall becomes a visit to a hospital, a family refuge and a journey through the justice system for everyone. There's a reason modern anger management techniques are about replacing inner negative dialogue ("I don't deserve this", "How dare she"...) to more positive scripts ("I can't control others", "I can't deal with this while I'm angry"), rather than making people hash it out and break stuff.
Those who say that hockey always has had fighting as a part of it are willfully blind to the fact that Olympic or international or NCAA or minor or rec league hockey do great without it. Hockey always prevented goalies from dropping to the ice too, until the rule changed. Sports evolve. Apologists say it's a fast-paced game with collisions, clashes are bound to happen, yet football and rugby to name two contrary examples are much more violent yet fights are not tolerated in those. To those who say that the fans are entertained by it, I would reply that some people used to be entertained by prize fighting and bear-baiting, and as a civilized society we've agreed that they are horrible, unacceptable activities which must be outlawed. So it will be for fighting in hockey, those who support it are on the wrong side of the debate and history; it will inevitably be outlawed, and our brains and society and children will be healthier and safer for it.