"Engagement Optimised Matchmaking" changes to matching algorithims to make inferior players feel better about their inflated rank, thus keep playing and being carried or autopilot losing. It also keeps dedicated, superior or marquee players, playing more because they have that many more games to climb to their desired rank, that they know they can eventually achieve.
Scarily enough the former paragraph is barely scratching the surface. It is really quite sad because gaming companies have been patenting (yes, patenting since 2016) algorithms in their matchmaking to achieve these results, gamers need to research "Engagement Optimized Matchmaking." These companies are doing a lot more than I have described here, even analyzing your playstyle and sometimes placing you on optimal teams (when it wants you to win and feel good) then vice versa. Placing you in games where someone one on the enemy team mains your main's counter or even placing someone on the enemy team that 9/10 games bans your main champion or champions.
Again I am barely even cresting the effects of this, and can be researched further on a personal basis. EOMM has been imposed, so that everyone plays more and spends more. It's divisive, deviant, scummy, and frankly not fun to be apart of. So next time you think, "Why after a 20-30 game win streak am I paired with people that are un-sportsman like and uncaring for the next 20 games?" Do not feel bad or unlucky, this is NOT luck or coincedence these companies are literally toying with the metrics of matchmaking to the point where rank means very little.
"...systems pair similarly skilled players on the assumption that a fair game is best player experience. _We demonstrate, however, that this intuitive assumption sometimes fails and that matchmaking based on fairness is not optimal for engagement._" This quote is from the link I posted to a very short and sweet article above. There are many more articles like this, some that go into more depth. The patents are convuluded and harder to read but they can be found as well. When fairness is not the number one metric in a sport the sport and ladder are not indicative of anything meaningful. For example: Would you watch a team of highschool football players with one NFL player, go against a team of highscool players with one junior high player on the team? I wouldn't.