Why is it okay to play multiplayer online games in a state too impaired to play well, when you would be slapped and sent away for doing it in meatspace?
If it is your own group of friends, and you all know you’re messing around, that seems fine. You all implicitly agreed on the level of play, and you had disclosure up front of who was drunk. When you play with strangers, that is the equivalent of joining the local pickup basketball game or sitting down to play chess in the park. If you are too drunk to make a shot, you will be forcibly removed from the game. Even chess players may get violent if you get a dozen moves in and then decide to giggle about horsies and how high you are instead of making a move.
In online gaming, people queue up or LFG while too drunk to realize that it is a bad idea to talk about how drunk they are. That’s not quite true; they have enough restraint left to avoid mentioning it until you are committed. It is a rare group that advertises “drunk DPS seeks understanding tank and healer to carry him.” League of Legends players wait until they die a few times to start talking about how high they are, rather than mentioning it during champion select. And they generally have enough sense left to pick a system like LoL’s where you cannot avoid with their choice to ruin your game without suffering some punishment or significant inconvenience. After all, the joke’s not funny if you don’t have anyone to play the joke on.
The usual refrain at that point is “it’s just a game.” But no, most people have the good sense not to do that where other people are in physical proximity, so they know it is not socially acceptable. Except apparently it is socially acceptable, because very few people seem to attach any stigma to it, and the drunk troll is not the only one who will go with “it’s just a game.” So maybe it’s me, but I cannot see an ethical system that supports making a negligent, unilateral decision that worsens the entertainment of most people around you.