There is maybe one solution to this. Add a penalty for the automatic afk-kick. Other than that, you can't avoid people from leaving, they have their reasons to leave as you have your reasons to stay. Nobody is entitled to judge anyone, you don't know their circumstances as they don't know yours.

Penalty for auto-kick imo should be implemented, if you happen to really need to afk imo you prolly don't have time for the duty anyways, it's very low of people to just afk and let the game kick them leaving the other players with hinderness and more time loss. It's not fair that you think that you shouldn't eat penalty because of reasons, and let others be punished instead. Just the same as fake dc. Although this is the ocasion where there should not be a penalty for dc, as again, we can't really assure if it's a legit power down or the player just clicking the "close client" button.

We can't get rid of a**holes sadly, we can only try to be better ourselves. Accept the roulette/duty rules as they are shown in the duty window, and if you want to leave, leave like a man/woman, not like an arse. If you're an arse, you will be remembered and if you were with me in party, I will vote "no" on your kick, I want you to come back and have the balls to leave like a person.