There's a player I've gotten dozens of times in friendly matches (small player base issue) and sometimes he quits immediately repeatedly, sometimes he waits until well into the match and then quits.
(Tonight I've gotten him again all three matches).
So I don't want to get him. I'll quit if I do.
It'd be nice to be able to have a 'ban list' of people you don't get matched with in friendly.
It wouldn't apply to other modes, where people could abuse it by banning top players.