There really needs to be a tuning down of both the speed and tempo of the game as well as the power creep imposed by runes, items, etc on champions.
Currently, games are too snowbally and usually leads to wins/losses where one team is vastly ahead of the other team and the stompage is just surreal with how big the kill differential is.
If you look at your 2017 Year in Review, you can compare some 'stomp' games you've had playing ranked with the games you're currently playing now. What I've noticed from my games is that in S7, games would typically end somewhere between 28 - 32 minutes depending if one side surrenders or not and both teams would take smart fights/trades which kept games going on for longer. Typically there was less bloodshed involved too where the kill differential didn't exceed 15.
Looking at my current games, I'm seeing anywhere from 20 - 30 kills difference in a much smaller time frame about 22 - 28minutes and players are throwing in the towel at a much earlier time than before. Even my damn Poro king games end in 9 - 14 minutes.
I'm hoping something will be done about this but... well, we'll see.