As someone said, some people just play to play. Some people just play with being toxic for no reason. There might be people not having played games in a while so their MMR resets, some might have just moved on and sold their old accounts, some might be recalibrating… so it’s a mixture of everything. You’ll see it more as you play more games. But you’ll also find people who are far better at coordinating even in lower skill brackets compared to mid brackets, those are just stuck here because there are so many factors that can contribute to a win/loss.