The reason the game is so toxic and not that much fun is that elo systems are inherently unenjoyable and I would argue unsuitable for team-based fps shooters. No matter how good you are, eventually you will stall and end up having to grind out those 52% win rates to see any progress, and whether this is you grinding gold to get into platinum or silver to get into gold, it just doesn't feel that great. Add this onto the fact your games are largely dependent on your stupid team mates performing their roles, communicating, picking stronger heroes and also taking into account map strengths/counter picks and then realising how dumb and uncooperative the majority of the population are, and you just have a recipe for extreme toxicity.
I feel like elo systems are a lot like the dungeon finder in wow (tangent incoming). Once implemented, you can't really go back to the way things were as people are used to the high levels of convenience and aren't prepared to accept less in what seems to be at least on the surface a modern advancement. But I would argue strongly that the dungeon finder whilst being more convenient is not necessarily better for a social game and for forging new friendships and enhancing your gameplay experience. Its certainly better for treating worlds as a waiting room while you queue up for the dungeon but overall I feel like the experience is worsened overall for having them in. Of course you can't go back because they're expected and its what people have become accustomed to, but at the same time its no wonder that dungeon runs have become a shallow shell of people not talking trying to rush through it as quickly as possible. Again, it was a chore to organise a group, deal with leavers, get everyone to the fucking entrance and start the thing, but on the whole I think that this lead to a better 'social' experience or whatever BECAUSE of the effort it took, and if people stood out you would want to add them to your friends/guild precisely because it was so fucking annoying. Friendships formed in mutual adversity and all that.
Imo ELO/comp queue systems are the same. Whilst they offer a very quick, accessible to all 'competitive' experience with no real forethought or organisation required, I think that the overall experience is just much worse than when people ran divisions and organised clan matches together etc. While more people can certainly play the game with competitive solo elo queue, overall I think the experience itself is just much worse because of this.
But at the same time, Im fully aware people aren't going to want to organise clan matches/have divisions/etc etc. and they just wanna queue up now and have the illusion of a competitive game that ranks them, when actually its generally far from it. And nothing blizzard will do, from banning people, to having scoreboards, to clamping down on smurfs (though I think a lot of the smurfing issue is that people genuinely get bored grinding out really small winrates and its just more fun to pubstomp at lower rating) will stop the toxicity because its just gonna exist in elo systems such as in OW.
I do think its an absolute joke that any game considering an esports scene let alone one that has league teams etc doesn't have a scoreboard, what a fucking shitshow