When AFKs are this rampant...
Now understand that I don't think Riot is doing the best they can, and I only say it because this is gonna sound very defensive of Riot. I want change. So...
I think Riot needs to blame the players. The system tolerates afk, and for good reason. We, the community of League, is attributed by some as the worst among the online games. The community needs to change its attitude. Standards have to improve.
They aren't quitting playing League, the AFKers are quitting with the players in that match.
Now I'm not saying you're the problem, but are you doing all you can to encourage your allies to play it through the bad lane phase?
Until you can honestly say you're doing your part... asking players to not AFK is actually borderline going to make it worse.