Global ranked matchmaking is a cursed concept in videogames. I don't think it can be made non-toxic, TBH. You take basically everyone playing the game, for what

Global ranked matchmaking is a cursed concept in videogames. I don't think it can be made non-toxic, TBH. You take basically everyone playing the game, for whatever reason they enjoy playing it (at any given time), and you chuck them all into a blender where the only metric is on average how good they are at winning the objective. On top of this, you're basically never going to be matched with the same people again, and no-one can really choose who they're matched with (blizzard has the concept but for some reason limits how many people you can avoid matching! And there's no 'match with this person again'). So you completely obliterate any idea of community or community norms around playing the game or acting, and chuck people wanting a serious game with lots of teamwork in with people who just want to fool around and not even play the objective, as well as people who just want to piss others off and will see basically no concequences for it. Even if you remove the really obviously bad actors who yell slurs and abuse at everyone it's not a recipe for people having a good time, because there's so many other ways you can get pissed off by someone else, and they might not even be in the wrong, they just want to play a different version of the game to you.