It is legit crap when you get to gold/plat/diamond elo. You can literally tell which team is going to win based on the win percentage comparison on OP.GG. Their team will have all 50%+ winrate while you get the boosted 33% winrate players. I shouldnt be able to tell which team is going to win just based off of looking at their win percentage. BALANCE IT!
Here are plenty of examples to prove my point:
Here we have a Yasuo Gold 4 with Silver 1 MMR yet playing with plats for some reason. What do you know, he feeds because Riot matchmaking is a joke:
A team with all 50+% winrate vs a 38% winrate, 2 49% winrates. Whos gonna win this one:
3 60+% winrates on the same team? How does this even seem close to balanced Riot:
The enemy team is being reinforced with a Gold V support:
Our team is being reinforced with a Silver 1 support: