As always: if leaving or sucking ruins a game for everyone else, your game is badly designed.
Only MOBAs have this level of toxicity. All MOBAs have this problem. Maybe lashing strangers together for forty-five minutes, in a zero-sum contest where half of them will lose, with so much inter-dependence and complexity that nobody feels responsible, is not great for the human psyche.
You can’t even kick someone. Losing them for any reason ruins the game. You have to tough it out, for most of an hour, after waiting however long just to start the game, and the inevitable loss will still count against you. No kidding people get wound-up.