"I had afk'd" - this is why you got leaverbustered.
The new rule is that if a teammate a) fails to connect or b) is afk for the first 3 minutes of the game or c) disconnects within the first 3 minutes before first blood against your team or d) afks within the first 3 minutes before first blood against your team, you are afforded a one time remake vote which must have the support of 2/4 of the remaining players. That vote is prompted in chat at the 3 minute mark and can be called for 1 minute after the prompt if I remember right.
There is no rule outside of that, and that should not and will not be implemented. By AFKing, even if your teammates already have, you're wasting the enemy's time. Even if you can't win the game, and/or the enemy's sure to win, they're having to finish the game. You are able to practice your gameplay still, but by AFKing you're both not doing that for yourself and robbing the enemy team the chance to use the game as practice. You are ruining the game potentially for others.
Two wrongs don't make a right, and an eye for an eye makes the whole world blind.