I do admit I have left some games while alive in the past.
The majority of those however were already thrown, i.e. when I was mafia and the very first day one or two teammates left the game alive. Continuing to play at this point is a punishment on its own: You barely stand a chance to win with only 2 or 3 mafia in total when early in the game, forcing you to waste your time for no reward (or fun) until you are "allowed" to leave.
The report that caused my ban here was exactly one of those games. Godfather left the game even while still in the lobby/role assignment screen. He already appeared dead on the ground as soon as the first day began.
A couple also did happen due to forced reconnects by my ISP when I was playing late at night. There is no fixed time when they do it (other than "sometime at night") so I can't really plan ahead for that.
And then very recently, after the new Steam client was released, there were a lot of disconnects from the server. I know this wasn't on my side as everyone else in the game after I joined back in reported the same.
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Punishment should be on the first leaver of a team, but not the rest. The remainder of the team has been punished already by the first guy leaving which doomed their chances of winning the match. Don't force them to stay in the already lost game. (Not that much for player-heavy factions like town, but extremely severe for mafia, given a ranked practice role list.)
That being said, please unban my account. Look at how many games I've played; look at the reports. The more games you play the more reports you will inevitably rack up, and a ton of them are for invalid reasons ("inappropriate username", we've had that one already) and the last one I've actually been voted guilty on has been over a year ago. You can clearly see that I am not using this account to troll or gamethrow on purpose. Thanks.