I have just now had a match where 2 out of 5 quit, it was a 3v5 and we obvoiusly ff'd. No way in hell I'm gonna play that through. I reported both leavers for leaving, of course, but what will they get? A 1-hour ban? And we got of course score decreases because we ff'd. And they only get a 1-hour ban for ruining the fun for 3 of their teammates who'd loved to take competitive seriously.
People don't understand that a lot of us, players, DO want to take ranked seriously and that they are just ruining the fun for all of us when they quit. Maybe don't let them play ranked for another day or a week even, deduct more points from their ranks or God knows what, but just stop them from ruining entire matches.