Are there any fighting games out there where an online opponent cannot quit until the match is complete?
No. And there never will be. Anyone can "quit" out of a match. Pull the ethernet cable, rip out your hair and bludgeon your console so you never have worry about pressing buttons "better" again.
This same discussion came up before in mk9. And the answer is the same: why is it only a waste of time to certain people who want to "get on to the next match" when they lose but not win? I'm positive that if those people had won they wouldn't be quitting out of matches because it was "a waste of time". I beat this DS senseless last night, and just about finished him with a second transition(first time I got someone through 2) but nope, opponent has left the game popped up. The only annoying part is that I wanted to see that transition dammit! I'm not gonna say I don't care about my record at all, but I will say its not enough to warrant me getting upset about it: I have great friends that I can play almost any time, and they'll play me regardless of my record. Hell, I don't even look at their records, I just know I'll have a good time.
Squeaker101 Espio STB Sgt Reed Scarlett and I'm sure when I play more of you more often my list will grow.
I usually only play for short periods of time. Every time I play I don't feel like having to go down my friends list and ask every person to play until I get a yes.
I don't ask. Just make a private KOTH and send everyone on your friend list who is playing that invite and hope for a bite.
It won't always work, but one can try.