In my experience games are longer than ever...
Riot, you keep making more and more and more snowball in the game. Higher damage creep, less tankiness, shitty towers, tower first blood, dragon advantages, and on and on. Yet from my experience games went from 20-30 minutes in Season 2, to 40-60 minutes in Season 6. Have you ever thought making the game a crushing miserable stomp for one side, only gives them initiative to drag the game out as long as possible?
Every game I am on the losing team somebody says the same thing. "We are losing, just stall out till 40 minutes so the items even out." (And often we do come back and win). This was never a problem in S2 unless your team had a hyper carry, which you supposedly removed those from the game. In S2 it was actually easier to close out games, but less miserable to be on the losing team. I'm not saying the game as a whole was in a better state back then, but at least on this front, I find the overall strategy of how games play out to be long, tedious and repetitive.
Winning side typically gets an advantage because of a lane matchup or an OP jungler. Takes objectives and dragons to snowball way ahead. Then either groups mid for the ace and win or uses split push tactics if they lack team fighting. Until they can get some picks/ace and either get baron then push or push for win.
Losing side typically is frustrated beyond belief and often feels cheated out of an early advantage because their laners were counter picked and the enemy jungler is Elise. Resulting in them deciding to stall the game out with defensive tactics as long as humanly possible until the gold gap narrows and they can try to turn the game.
This is like, every single game I play. Usually resulting in a 40+ minute slugfest.
Now this is all speaking from personal experience but... I don't know what else to speak from when it comes to how the game feels. It's bad enough players spend 90% of all fights slowed by 40%+ movement speed(fake and exaggerated stats) making the game feel slow motion. But when it drags out for nearly an hour or even over an hour. It just feels bad...