It's not matchmaking.
It's Jungle and support changes which both became polarized roles in every game, where they didn't used to be.
If a Support or Jungler falls behind, there's no catch up mechanic anymore. Not only can you not XP, you can't gold either.
You also can't compensate for poor teammates anymore, because your success is tied entirely to theirs as these roles now.
And then, there's the fact people among 3-4 elos bunched together in each elo right now because our placements are now a remnant of the state that went into effect when positional ranking (Season 9) was removed where baseline MMR dropped with the introduction of Iron.
Game basically just needs one person who is a smurf to have a good lane now, and the game is over, because a team can just huddle and push.
I just had a smurfing
last night have 219 CS by 14 minutes, vs a Veigar who didn't even counterlane yesterday.
My team consisted of

How do you think that worked out, a smurfing Viktor vs no spell shields, no mobility skills, and a 13 CS score for the first 10 minutes of the game (8.6 overall)? He 1v5'd, and could kill people without even needing anything more than his ult. He could flash over a wall and 1 shot 123 Magic resistance. He got to freelo turrets. No one could get even close to drake. No one could trade him or even 1v5 him, because he simply didn't need his kit to kill anyone. 1 shot, gain shield, laser someone else. R someone else.
I got bot and top ahead. His bot/top sucked. Even got early drakes. Didn't mean crap, because he was Viktor, and smurfing.
https://na.op.gg/summoner/userName=MegaBadNublet