The problem with the punishments is that the reasons for disconnect aren't always because of the player. Storms screw with internet connection sometimes, Riot servers are unpredictable, irl emergencies do happen (my brother flooded the kitchen once,) you can't crack down on people who're just trying to play the game like you and that crap happens. Wouldn't all of you look like dunces if you randomly disconnected after implementing whatever punishment you wanted for afk's?
I agree with all of you that afk's kill the game, but unlike games like FPS' or MMO's etc. there's a ranked system built into this game which makes players connected to fill in for the afk unfair since the champion couldn't be accounted for at pick or the player gets stuck with a champ they don't like, or (if you have something like Teambuilder) there's not enough players who've decided to fill in for that champ to fill the spot. The ranked scene causes many problems that other games that've found ways to handle afk don't have to deal with. There's no precedent for Riot to follow as it's unfair no matter how you look at it.
It's probably not that Riot isn't like "wtf do we do about afk's" it's more like "what can we do?" only to be met by dead silence in board meetings. Honestly, think about it for a minute. What is a fair way to compensate for afk's? You can't fairly punish them. Period. That requires a case-by-case basis and none of it can be proven. No one has the time for that. How then do you make it fair for the other players affected? That would seem easier, and indeed, it is easier than impossible, but it's still never going to be perfect and even with a fill-in system, there will be complaints of things being unfair, it's bound to happen with a system like that. League of Legends isn't entirely skill-based like other games, you can't just find a good place to camp, stand back-to-back and fend off the enemy mob until someone else connects and joins your team, if you do that in LoL you lose all your turrets. The reason these discussions keep coming up is because no one has found a solution to the problem yet -if one can be had. LoL suffers uniquely just because of the way the ranked system is set up in conjunction with the highly team-dependent nature of it. You have to deal with a lot of issues in tackling the problem that may not reconcile with the state of the game. I see no way to fix it without altering the game significantly which isn't something anyone wants. Its accessibility to ranked is a virtue. The team-aspect though will always cause problems in conjunction with rank though whether afk or not. That's just an issue of team-based games of any kind. There just usually isn't the weight of rank being put on it in other games barring tournaments in which afk'ing isn't an issue.