Can M0's please drop loot only off final boss

Obviously. The difference is in your model of “rewarding loot for staying a full run” just punishes the good players in those situation unduly, actually incentivizing bad actors to continue bad behaviors as they get the joy of knowing that either the group deals with their trolling to get the extra loot, or they get punished by getting less loot just to rid of the bad actor. Either way, the trolls actually win in that situation.