the quitting in stock matches is totalyy understandable i will tell you what happened
3 stock 4 players
only me and another knew how to fight properly we target each other of course while the 2 noobs duck it out eventually me and him got killed and the 2 noobs remained, they didnt know how to use the supers effectively so they kep failling and failling 20 mins later the match still going if you are the host of course you want to leavue no matter what since stock s dont have time limit they could just be there for hours and its stupid the host doesnt migrat to the standing players in stock matches
In unranked, there should be no penality. Superbot should have had host migration from the start, especially since they support stock in unranked. If someone is out, there is no reason for them to stay. I.e. the first player to die is unlikely to wait 5+min when they could just queue for a new game.
However, maybe they should do what developers did with Lost Planet 2. In the matchmaking screen, the reported the DNF% (Did not finish %) of each player.
That way, when I match starts, rage quitters will be singled out. Anything above 10% would just be shame many players wouldn't want. They could also reset it every season. Additionally, in stock when a player days, it should just say Defeat and give them the option to leave without penalty.