Riot's vain attempts to introduce outplay potential
These were the champions released and reworked in 2015 and 2016: Kindred Gangplank Fiora Poppy Ekko Bard Illaoi Tahm Kench Jhin Kled Aurelion Sol Ivern Taliyah Camille Shen Taric Yorick
In my opinion, these were the golden years, where most to all of the champions had something new in terms of mechanics, were relatively balanced (ignore immediate release cause anyone around in 2015 will remember release Ekko) and wouldn't kill you in a single ability. (also notice how only six of them have out of combat dashes and none of them have invis). Compare that to the champion releases (and reworks) in 2018 and 2019: Swain Akali Irelia Aatrox Kaisa Pyke Nunu & Willump Aphelios Senna Yuumi Sylas Qiyana Kayle Morgana Neeko 5 of them have invis and 6 of them have out of combat dashes (Irelia isn't out of combat but still insanely mobile in combat). And almost every single one of them with the exceptions of the tanks and supports: Nunu, Yuumi, Kayle, Morgana, can or has one shot someone.
Riot is constantly pumping out new champs with 'new' stuff to introduce outplay potential. But really, it's not new, and there's no outplaying getting one shot. As much as it's not that fun if every single champ has a dash and a stealth and an execute and can 1 shot you, I'd be tempted to say the major lack of true enjoyment in League for me comes from the power creep. If Akali couldn't one shot someone and you saw an Akali play around her shroud and 'dance' around everyone, it would be the next "Faker, what, was, that?" But everyone has dashes, everyone has invis, and everyone one shots you. There's no skill expression in killing someone within 0.5 seconds coming straight out of invis from 2 screens away. Faker's famous 1v1 was awesome for a reason, no one had seen a skill level that high. He didn't one shot Ryu, and he 'danced' around him perfectly.
You'd also be surprised as how much more viable comebacks might become if your entire team doesn't just get one shot by that Vlad or Kat
Nerf damage across the entire board. If you nerf damage globally, you will be surprised at the level of skill expression that re-emerges. Because mages don't get one shot and actually have an opportunity to fight back and outplay the assassin trying to kill them, you'll see Cassio and Ori and Syndra re-emerge because they have insanely high skill caps, and insanely high outplay potential. And if that assassin still manages to get you, you can at least sit back and think, "That Zed is really ****ing good, he landed all his q's, slotted his e's and autos perfectly into his combo, and used his shadows and flash to dodge everything I had." That's, an outplay.