Ranked AFK/Quitting Punishment

Playing a match as jg with Zilean and Draven in bot lane. Draven wasn't having a very good day against Miss Fortune and Taric; Zilean wasn't very helpful to the cause somehow. That's not their fault, just outplayed I suppose. But....

Draven dies a couple times. Zilean, rather than giving a little advice or persevering through the bot lane, quits the game. Draven then gets a little more hopeless.

I think there should be punishments to deter the afk/quitting behavior since what is in place currently is not working (because I've seen about 5 afks/quits in my last 12 games). So what about a demotion with every afk/quit and 5, 10 (insert number) games with an LP hold with a win but still get a loss of LP when you lose?

Could go with maybe even the AFK gets demoted, and no loss of LP for the poor 4 who got screwed over. The AFKs/quitters are too frequent for me to even make it to 100LP let alone win 3 for promos...

And I know someone's gonna say my idea is bad, it's something I literally JUST came up with last night. So constructive criticism, please. Permaban should have got these inconsiderate bums by now, that's why I am bringing this up.