Inting/AFKing/Smurfing is a massive issue(In mid diamond at least).

I was in D2 promos 2 days ago, and have dropped all the way down to low D4. In the span of 25 games I've had to dodge at least 7 games due to troll picks like Disco Nunu, ADC Zilean, and jungle Swain. I've seen my friends and myself ping pong around mid diamond this season more than any other season due to horrid matchmaking and general trollery.

My last game I lost because our Lulu went 4 boots while Vayne inted, game before I won because of 2 enemy AFK/DC, game before that our jungle said g"i dont like this mid so imma afk" and left, so on and so forth.

When games don't have a troll/AFK it's almost always offset by a smurf and or booster. I've had games in D4-D2g where there are more smurfs than normal players (Virtually no normals, unranked last season %60+ winrates). It has come to the point that I'm playing Dota 2 to unwind from the experience that is solo queue.

Riot had gotten fairly good at faster balances(Even if they miss the mark sometimes), but their ranking system is still incredibly wonky and unforgiving(In mid diamond atleast).

A side note, I have a couple smurfs to play with real life friends who only ranked and no matter the elo there are still many unwinnable games due to trolling.