I don’t know anything about Spellbreak so I can’t speak to the steps they took but I believe OW does do a good job at moving skilled players out of low-ranks quickly when they’re playing too well.
From my own experience, I’ve leveled two alt accounts on PSN and I started my PC account after a couple of years playing in GM on console. On each of those accounts, I tried my hardest from the beginning, even while leveling up in QP, and was very, very quickly moved out of lower lobbies. On PC, I destroyed newbies with Tracer for exactly one match in QP and was put in a lobby with masters players on the next game. After placements in comp on every account, I was getting 50+ SR per win to move me up quickly through the ranks. It actually defeated the purpose of even having the alts because I was only able to play comp with my lower-ranked friends for a few days before I was ranked too high to queue with them again.
I think the problem in OW is not with people whose skills aren’t being recognized by the matchmaker, it’s people who are intentionally underperforming until they decide to start stomping people. We can help with that by actually taking the time to report throwers/de-rankers because I don’t think most people do. When I’ve asked people to in chat, I’ve heard a lot of “Why report? It doesn’t do anything anyway”, which is a self-fulfilling prophecy if nobody takes the time to report.
As far as my experience with other games, especially FPS games, I’ve never played one that didn’t feel wildly imbalanced as matchmaking goes.
It’s a matter of competitive design. In OW, SR is win or lose, all or nothing after placements. In Apex, for example, every new account starts competitive at the lowest rank and has to work their way up through the ranks. There’s pros and cons to that. The biggest con is that there’s no throwing needed. Any top-level player can start a new account and immediately start crushing lowbies in Bronze IV. A pro is that you can’t rank up without pulling your own weight because kills/damage/etc. are factored into your results and your own performance is the most important factor, not the outcome of the match. That makes for more consistent skill levels at mid-high ranks.
Blizzard works on the matchmaker all the time but it’s hard in this game because of how much skill isn’t quantifiable. It’s not like Apex where kills/damage are all that matters. I don’t think they can be so easily compared. I’ll say, though, that five placement matches isn’t enough to accurately place someone. On the other hand, I don’t want to have to play 10+ placements for every role every season. I’d be in favor of changes to placements for already active accounts, though, to accommodate that.