I've been playing on and off casually since 2012. Always liked to dabbled in ranked, but it's always seemed to me to use other people as either stepping stones in your games or progress gates.
You used to see some people complain about the match maker here and there, but now just look how many there are, and it doesn't matter what division they are in.
Now people say, ah yes but due to the TFT the quality of players has dropped in ranked overall. Well you know I find it real strange that after say 4/5 games of trolls ,or afk'rs ,or children bickering, suddenly I get a few matches where my team is fine again. So it seems to find ok players when it thinks you deserve it, but when your times over whoooaa boy you're in for a grim time.
It's honestly no wonder people go crazy flaming etc because it's enough to make you insane and really frustrated. The game is currently so aggressive with when it decides what quality of a team it will put you with you can almost time exactly when the rough games will come in.
It's also very clever when you think about it, as when you get that game with the afk'r etc more than likely your KDA will suffer as you try to keep the game going. To keep a good kda in those games (or lets face it sometimes kill at all) you'd have to kill a few people and then just stay in base, which I've seen some do.
TLDR honestly just don't waste your time, the game is in the worst state I've ever seen it, and after trying all I can think of to try and get through the rough games (various champs, roles, etc) I think they just want people playing as much as possible, and win just enough to keep you hooked...like a Casino does where most of the time all the games are statistically geared towards you losing eventually.