I have been prevented from playing Dota 2 for 1 year. Asked to Steam support the reason for this ban, they answered me that this punishment is related to one of those actions:
- Deliberate actions to artificially boost MMR of the account
- Buying, selling, or trading accounts with boosted MMR
- Creating an unfair competitive advantage through third-party programs
- Circumventing low priority by collusion with other users or bots

I did nothing of the above. I just stayed afk for some games cuz my team literally told me that they would have feeded couriers from min 1. This happens quite often in low priority and i simply refuse to play games with intentional game ruiners.
So, if you tell me that refusing to play with acc buyers and griefers is worth 1 year ban, then i'm ok with it, i'll just play some other moba. Otherwise i think a mistake have been made.