This is a horrible idea because honestly a team wouldn't let the other quit. If I spent 10 minutes in a game and two of your players rage-quit, I wouldn't say, "Meh, no biggie, 10 minutes wasted, but for YOU I will drop the win ." Players might use the option once or twice, but once they see it happen over and over, they are going to be JUST as tired of leavers on the opposite team as they are currently with them on their own team. It would just cause even more games to be disrupted.

Plus, this would have to be agreed upon by 5/5 on the opposing team, otherwise players would just be extremely upset that their team-mates cost them a win.

This is the butter to my bread. With an 80% vote, a draw/remake/etc could work nicely. How about at the 15-minute mark?

sounds great on paper, will NEVER happen

GREAT idea, but a draw option wouldn't be better?

If you do decide to thiunk about this, only allow a mutual surrender within the first 15 mins IMO, after 15 mins its complete warfar and can no longer have the option....

just have a tie part in between wins and lose. it will have less rageing happen. and maybe less people would quit the game

thats not gonna work out too well... if a player leaves then his whole team will have an increase in gold/sec.. if the team now turtles and prolongs the game. the player can then return to the team and the team will now have 5 players with more gold then they should have.
the only reason why DotA does that is because you cant rejoin after you leave or are dc'ed for any reason.
LoL creators obviously already looked at this and made it so a player can rejoin the match if there happens to be an issue with his connection/computer.

+1 bump this for riot games to see