Ok. Its really simple. Objective rating system + No in game data is used. Look up Elo on Wikipedia your showing you did not do any homework on the topic. GJ copypasting the same BS argument used on various boards for multiple games. Not just Leauge, this complaint is common in Dota, halo, HOTS, basicaly any team game. Get it? Your "evidence" is irrelevant because your using subjective judgment for your raiting when discussing an objective system. Issues with the MM are going to be about curve and size of a class interval as well as if any bells and whistles riot adds make negative impacts.
Meanwhile, Objective systems. There is an average level of skill in a finite # of players. Averages are naturally occurring mathematical concept. What you need to understand is your rating is constantly being compared to the average of whats in the MM range your at.
A "1400" player only has that value because of the proven history on their account and the context of the raitings they are playing with and VS.
If you want issues that make negative gameplay, massive amount of them are due to player behaviors. A system that Riot needs improvement on and should have a dedicated Red to engage with the community about.
Their duoing Range is way to wide and not off MMR. It should be, I don't see any logical way to have reasonable math for the ranges they allow MM to let duo operate at. Its not that it breaks the ladder, just that it makes Mismatches which are inherently lower quality games and will create skill gaps between a solo and duo for the que on individual accounts.
Demotion protections massive for Division 4.
Now. forced 50%?
YOU DAFT FOOL! You cant use MMR to build skill from WR if the WR does not reflect skill. Its pointless! That's not the metric that you would use and not the system you would use.
Plus any "nefarious" reasons riot would want a forced WR? Name one and what's required to accomplish it. Odds are I can tell you the easy way riot can just have functional Elo style systems to do it.
Also for gods sake don't you dare say longer time to climb, have you ever seen folks graded on a curve? The "average" players time to top is eternity long so please don't fucking say riots trying to make the grind longer then forever.