A suggestion for AFK punishments

I'm a player who just lost my promotion game because a player decided to rage quit at lvl 1. No one even talked yet and he/she just AFK because he/she was killed by wraiths at lvl 1.(or its because theres a friend of him/her on the enemy team.) This is not the first time I have lost my promotion game because of this reason so I wanna just post my personal opinion about AFK/Rage quit.

I don't know about how a company like Riot works so please do not say bad words about me if the ideas are stupid.

My suggestion is that if a player is AFK for over 15 mins or 20 mins, that counts as an bad game. So when this type of games happen, the winning team will earn less LP and the losing team will lose less LP. If there are players in promotion games in a bad game, it counts as 0.5 a win or a lose. If a player wins 1.5 or 2 games in a BO3 promotion, then he/she is promoted. If a player lose 2 games in a BO3, then its a failure.

There must be more things to be considered about i guess. like what if a duo afk intentionally because he found it is going to be a loss.

Just a brief suggestion from a lol lover