Oh, I’m sorry. I forgot you are the exception to the system
It’s ELO. Matchmaking is determined solely by your ELO rating/SR. Nothing else. Maybe an addition to toxicity, I don’t know. There is no “we will let you win 3 times and let you lose 3 times”. Have you ever talked to someone addicted to slots? You can’t imagine the amount of patterns those people see in their random images. It’s literally the same argument. The system doesn’t push you anywhere, you’re just unlucky. I’ve had several bad teammates in a row as well, and I’ve had several good ones in a row. Then I’ve had a good team and a bad team, then I was bad and after that I was good, etc., you get the point.
I can try and tell you why it feels that way, though. It’s because Overwatch is one of the most teamy games out there, also you can’t check how your team is doing and who is playing badly. But one bad player can lose you every game, just as one good player can make you win every game and make it look like you’re playing with 5 GMs. Overwatch has this weird feeling that if you lose, your team looks like they are Bronze, but if you win they combo ults like you’re in Diamond.