Loss prevented when teammate DC/AFK

As a long time League of Legends player I have learned that having someone DC/AFK from your game completely ruins that game. Within my recent ranked games I have lost many of them due to players rage quitting, flat out leaving the game or disconnecting. There needs to be some type of lose prevention for this. A punishment should be given however in certain circumstances DCing is unavoidable. Thus I propose if a player is DC/AFK for longer than 2-5 minutes the team with the DC/AFK should have loss prevented if they end up losing. The player who commits this crime should be fully punished with full amount of LP lost and possibly more. On the flip side if the team with the DC/AFK player wins they should be rewarded for winning a 5v4 game as the requires skill and teamwork, the reward should be something on the lines of bonus LP maybe 5 or so. Having a teammate leave the game if the most frustrating thing you can experience worse then someone feeding in my opinion. I understand in come cases a player disconnects from the game and they cannot control that, so if possible they should not be issued a punishment however, there would be ways to cheat the system if that’s the case so maybe not. A player should not be punished for their teammate decided they don’t want to finish that game. Also I know loss prevented is already a thing as once my teammate (a singed) inted the game so hard my team lost no LP