An unbelievable number of smurfs / boosters...
I decided to actually put in games this year and see how far I could climb. After a few seasons of being low gold with around 75-100 games, I've put in over 200 so far this year with a 54% win rate and climbed to plat 3 (and lost promos to plat 2 once).
However, ever since that promo series, I've seen an unbelievable number of players who are either challenger/master smurfs, or are getting boosted.
No word of a lie, in my last 9 games in a row there has been a player currently ranked between gold 1 and gold 5, with a win rate of over 70% (some as high as 97%), with plat 2-3 MMR apparently. And that player has hard carried 8 of those 9 games. To the tune of making their lane opponent go 0/8 or worse. In mid plat elo.
They normally say if you're exactly as good as your elo, you'll win a little over 50% if you never AFK or troll because there's a 5/9 chance it will be on the enemy team instead.
Except now? It's more like "if you're not the challenger/master tier player, you'll win under 50% because there's a 5/9 chance that the challenger/master player is on the enemy team".
I always ignored all the complaints on these boards about smurfs because I figured they were rare enough that it wouldn't affect more than a handful of your games and ultimately wouldn't affect your ranking. Seriously though, my last 9 games in a row have had 1 or more players ranked in gold (3 of them had 2) who have insane win rates and played really well.