Nah, you're just making that up. My entire flist is mostly high ELO and if I ask any of them they prefer S3 more. I've heard double say the same thing tons of times in s4. I was high D1 in S3 and I'm Masters now, I barely play the game, the people in my games are commonly hilarious bad and use stupidly easy champions like udyr/yi/leona/braum/janna/fiddle/graves/whatever. Comparing it to a time everyone in my ELO would use heavily based mechanical champions like lee, elise, vayne, twitch, draven, zed, jax, riven, twisted and so on is just insulting.

S3 was literally out playing people, carries would actually hard carry. S4 turned the game into the league of tanks/doran shields for half the season. Supports with zero items were tanky to the point you literally couldnt hurt them and it was a waste of time trying. Mundo/shyv was the meta for an entire year. Went from having insanely skillful duels, to this: https://www.youtube.com/watch?v=-eIp7BlmiWU

S5 is just a less dramatic version of the video above, they nerfed stuff like that a bit but it's essentially how the game plays out now. Before, like in S3 worlds, top players like Royal Tabe literally only had boots 30 minutes into the game. Lustboy was the same. These guys actually had vision control beyond comprehension of the average support today. Buying a FOTM + sightstone + mobis and laying 3 wards everytime your shit is off CD isn't "in depth/hard" the game is a joke now.

Sure it has more shit to learn, but actually being SKILLFUL at the game doesn't matter as much now. Everyone is more passively strong/tanky and assassins/duelists/fighters/mechanical champs have all been nerfed insanely hard, almost every single one of them. The game is more about slowly playing for 5v5s and taking dragons everytime they are up, it's far less individually based/mechanically based.