Short comment to the post made about "Loss prevented with AFK in team and more LP if you win with AFK". You can see it here : https://boards.eune.leagueoflegends.com/en/c/off-topic-en/sYHkOrxN-loss-prevented-with-afk-in-team-and-more-lp-if-you-win-with-afk
See the ELO as MMR in this post, its the same thing.
The MMR system is most likley based on sort of an ELO System like in chess. For those who are more interested, click this link and watch the formula https://en.wikipedia.org/wiki/Elo_rating_system.
In short : Players meet each other for a match and a formula is used to decide the outcome of the game based on their ratings and hence given the new ELO/MMR points after a win or loss. You CANT give someone ELO/MMR points and not "take" away ELO/MMR from the opponent, the formula dosent allow that, if you do so the formula will be invalid and the whole ranking system is at fault.
You cant either "give extra" mmr rating just because someone afks, cause the formula is predecided before the game begins on a set of rules.. Again the whole system will get invalid.
To give an example irl :
Let us say a chess player is really really sick, and the chances for the player to win the game is slim to none, but wins the game he dosent get more ELO rating just becuase he is sick.
Im not syaing its impossible, but it will shake the foundation of the MMR system, and you will get artificial MMR ratings just because some people "jump" up and down randomly due to afks etc.
Im not saying it shouldnt be done anything about it. Yes it sucks, yes i also hate it, but you need an embedded formula that works in the core to make a ranking system work. If you gonna implement loss prevention and extra mmr you need to make additional formulas to make a work around so the ranking system stays valid. I dont think its easy to do so, even then you need to "patch" the formula for outliners the whole time.
Maybe hard post to grasp, but i hope it made a bit sense.