Perfect reason why you don't surrender when kids ragequit.
Look, I"m all for playing until that Nexus drops. If you think you going to lose why not keep trying and just play smarter. Though I won't go through the full details of this match but lets just say Flex decided to give me a player who picked a top ban and didn't know how to play her. Blame team and assume their mid has scripts..and rages out after I told her to just relax. "GL winning without me.." Something on the line of that. What makes the game funny was when she did leave the team worked better cause we didn't have a feeder.
Personally I think if you win a 4v5 due to someone leaving that person should just be auto banned.
Moral of the story, keep playing. You play smarter, you can win even with the odds against you.