Except, by leaving, you then get ZERO credit for playing the game. no xp towards leveling up and getting your other custom classes, no xp towards completion of that seasons pass for unlocking the latest premade classes, and no coins towards getting anything in the store like gear banners emblems etc. If you're a HUT player, no XP towards the XP path and no coins towards getting new cards in the auction house or whatever. You may say so what? But that is your take on it, other people might be interested in this sort of thing.
THIS RIGHT HERE though is why I say you need a mercy rule for this game. A five goal rule that if you go down that many, the game ends. It would make matchmaking quicker to find more fair games because the lopsided matches would be short and the fair matches would go the full 20 or so min it takes. It also takes away the humans mental defeat of having to quit out of a game and get penalized for it with a dnf%. Now some I have talked to argue that 5 is unfair and it should be like 7 or even 10, I can comeback down 5 goals... To that I say, if that was the case (and maybe it would happen an extremely small % of the time) than you probably shouldn't have gone down 5 in the first place.