Rubbish, it's garbage at all ranks and it's also fun at all ranks.
My highest SR is 3780, so mid masters. At that rank I had games with 3 mercy 1 tricks on the team, only one of them can pick it, one goes Symmetra, the other picks Torb. (attack on route 66) what followed was definitely a garbage game. I also have a game where a clutch grav up a wall pulled their team out from Orisa shield and our DVA stuck his self destruct right under them, 5k and a win in overtime. Epic, fun, brilliant game.
I've watched streams where GMs and T500 have games ruined by 1 tricks, stream snipers, throwers and clearly boosted players. I've also watched GM games and marvelled at the team work and level of skill, really close overtime victories or defeats. No salt, just great play and close games.
Pattern repeats at diamond except everyone shouts more and thinks they should be masters and their team is holding them back.
Plat is pretty much full of angry people from my experience. Diamonds abuse them for being plat scrubs, they call gold, silver and bronze players trash and generally don't work together. But some games, out of nowhere, someone pops up on comms, communication ensues and teamwork happens, so still fun games to be had.
Below that, I had no idea.
The game is what you make of it at the end of the day, sometimes you need to be the guy to try and get a strategy open, call out a target. And just enjoy it. I got my highest rank off tanking. Now I play DPS and I'm sitting around 3300-3400, I'm not getting angry because I can't reach masters as DPS, I'm just not good enough.
As for the mercy and junkrat changes, about bloody time. Reddit bandwagon aside she was stupidly overpowered and now people are realising they can't just play dumb and get ressed. Positioning matters, deaths count more again, and she is far easier to kill now she doesn't ult into a super fast moth. I stopped playing comp during the mercy meta because you either didn't have one and the enemy did so it might as well be 6v7 or 6v8 or you ended up stuck with 2+ mercy one tricks on your team who couldn't play any other character at anywhere near the same level, so you effectively got stuck with a DPS in a game 500SR above their skill. Now Ana is being used again, Moira is really fun, lucio / rein are back and Zen is still just as good.
(before anyone mentions it, yes I could play mercy when the team didn't have one, and sometimes I did, but it was so boring I just gave up on comp for a while)