The penalty needs to be severe in my opinion. Leaving because your not getting 3 or 2 chests is terrible.Not only do you not get loot you also ruin the run for everyone else. You cannot be replaced and the keystone fails and if you are the tank or healer no one gets anything at all.I would argue that leaving one causes you to forfeit your loot from the weekly chest. Its a focused and semi competitive dungeon run.Some guild members reckon you should be locked out of mythic+ for the week.It is a serious problem when one person can just screw over 4 others completely and screw the guy with the keystone for the week. No one wants to join my +4 arcway depleted. Why bother, you dont get anything from it.