Riot Still doesn't Punish Afkers in Ranked Competitive Play

I've been playing this game since Season 2. And have spent a shitton of money on rp over the years. Why can't riot support players like me who just want to play competitive ranked games without afkers? I know its an impossible proposition to completely eliminate them but the penalty for losing such games needs to be significantly less. And the punishment for those who afk need to be significantly greater. I don't understand why riot cant do an INSTANTANEOUS 1 week ranked ban for afk in a ranked game. This will not bar you from playing normals or aram. But this sets the precedent that ranked games are too be taken seriously. The current system rewards afkers and punishes everyone else.