Again you’re failing to understand the problem. The problem is that you’re not being put on a team with players of your skill level.
Yeah sure a game is lost because one team plays better, no one is questioning that.
But if you’re a masters dps or support and you get matched with a plat tank on your team who consistently makes bad plays regardless of the reason (low game sense, bad mechanical skill) it’s almost inevitable that your team will lose because they play worse than the other team. That’s the point, the person playing next to you isn’t as good you. Or you aren’t as good as the people on your team and YOU’RE the one constantly making mistakes that cost your team the game, either way.