Riot, you have to make the MMR variance smaller when matching people!
So it's obvious how matchmaking works. Everyone has this handy MMR score none ever gets to see for some weird reason, and then when people look for a game the system pairs people with value X in the same game. But, because that would take forever to find ten people with your exact MMR, so the system has some variance in it that ranges from, let's just assume X+5 and X-5, and then tries to make the total MMR on both sides even. And that's perfectly fine as a system, the problem is that the variance is JUST TOO BIG.
Imagine there's a game, and one side has a pretty "normal" MMR average, the other is a weird mix of people being either in the high end or the low end of the variance. Now, the player on the "low" end is already set up to lose, as he's thrown on a playing field that's ever so slightly above his level. "But the higher level player should totally cancel that out, then, right?" you might say, but let's be real: having one bad person on your team is so, so much more impactful for the game than having one extremly good person. I remember the days of Season Two where "just mute them all, do your thing, and solo-carry their sorry asses" was a thing, but you can't do that anymore, as Riot wants this to be more of a "team game".
This is why games also have become so stompy, and also why there's always party on botlane: more players are there, the chance that the "bad one" is there is just higher. Usually a "stomp" doesn't really start with all lanes totally crashing down. It starts with one person getting fed, getting an objective lead, and THEN everyone has an advantage and stomps the other team. But it usually starts with only one person just shutting down their opponent in a way that shouldn't be possible in a somewhat evenly matched game.
Especially in somewhat higher ELOs like Plat or above where people KNOW how to actually keep a lead and play it out without throwing, these games are just sad to look at and pretty much a reason we have a surrender at 15 now - because the game is just decided there already in some cases.
These games are usually not really fun for anyone. Not the player getting crushed early, not the rest of the team who barely had a chance to play before it was even decided... imagine playing a somewhat solid toplane and at 10 mins your botlane has a collective 8 deaths, lost two towers, and an infernal drake. Your input in this game doesn't pretty much matter anymore as it's already over. It's pretty much the same when you are on the winning side too.
Yeah you win, but not because you did anything, but because the others found some poor soul to stomp into the ground. I'd rather win through my own effort and skills, thanks.
And how to fix this? Simple - reduce the variance for matchmaking, to allow for more even games. That might mean an increase of queue times, but I'll gladly wait a few more minutes if that increases the quality of my matches. Dunno, if it is X+-5, just tune it down to X+-2 or whatever the numbers are that the system operates with.