Not just on quick matches, Ranked too, it's pointless because you will still lose BP unless you were by chance host. Whenever I'm in a match and an opponents teammate is disconnected before it starts I'll back off and allow 1v1, unless they try to get some free AP off me because then they're just asking to be double teamed. Also what I don't get, when someone whiffs completely with their level 2 and just leave immediately even though it's still early in the game.
Solution: If you're going to rage-quit or be impatient and not wait if knocked out in Stock, then either go play Kill or Time Limit.
Side-Note: Most hilarious rage-quit I've seen is when someone raged after 1 death... Not being knocked out, but just their 1st death, the 1st death of the match. Funny thing being is that I got it with Jak's one after he (Raiden) did an Air-DownT and slid to me and I did my one after he reached me -- he rolled into a wall and was caught by the linger of my Level 1 when he stood up.