If Riot makes it so that it takes 7/10 votes to work with all leavers counting as a vote for yes, then it would only take 2 decent people to be on the other team for it to be declared a draw and the other three that want an easy win can screw off and make a new game. If you can't show good sportsmanship then you will be forced to by the people that can.
Only alow it after the 25 minute mark OR if there is a leaver for more then five minutes and it has to be initiated by the team with the most leavers (if there is an even number of leavers on both sides, the game continues as normal).
Both teams get the same amount of IP/EXP, a mix of a flat rate and possibly a bit more from your kills/assists, with the leaver(s) getting nothing. The match goes unrecorded because it doesn't matter.
This is easily do-able and I'm honestly surrprised that people are arguing against the OPTION of it. If you're afraid that it would be abused is some way, how about you put your energies towards figuring out how to make it NOT be abusable?