Oh it's real. Most people here will poo-poo it as conspiracy theory, but it's all over reddit. It even groups trouble makers together so they can be in hell together. It makes no sense, b/c it drives it's own toxicity...but yeah. Intentionally was like, model overwatch citizen on my smurf account and even though it did recognize I was a smurf after like...2 games and start putting me with fraking GM smurfs, overall my account staying in good standing has made me have much smoother games.
I've had less leavers and throwers and finally broke my plat curse to reach Diamond. And statistically looking at my play on two different accounts with the same characters, my statistics are very close but my rank is not. Just finished up like a 10 game losing streak on my main (*toxic) getting curbstomped whereas I play my clean, smurf account and shit on everyone with widow and mcree. It's definitely a rigged system to try and get skilled, less toxic people to the top out of the 'scum' so to speak.
Sure, just one anecdotal case...but I've played over 200 games on each account this season. I don't suddenly play different on one account and I play the same heroes on the same maps every time. The rank difference between my accounts are 2546 (main) 3009 (smurf) with my season high being like 3159. That's a 600 SR difference for playing the exact same, so the only variable is Blizzard's matchmaking.