LicorLet me put this as clearly as I can. Spending money to get higher stats with runes that people can't get as easily without spending money is paying for an advantage, you can't change that fact.
You are making it sound like you need to spend months of playing to acquire those same runes, whilst in reality it takes a week, literally a week to get them - and even that if you really want them. I've played without runes for the first year because I couldn't be arsed learning them, until my RL friend did a tutorial for me. They do make a difference in a close battle, but I wouldn't call them game changing, nor would I call LoL a P2W game because one guy got them a week before me.
You can buy all the champions in the game, but it's still going to take you a lot of time to master even a third of them. You can have all the champions, it matters little and it doesn't affect your gameplay. If you have a pool of 100 champions and you know how to play with 10 of them, having another 90 won't help you in your game because you have no experience with them. A blind man is a blind man, no matter how many walking sticks you give him.
The ONLY benefit I can see, for someone who has money, is that you can acquire those runes literally a ten day or so before the player who started without the money. If that makes League a P2W game I might be living on a wrong planet then.
Idk man maybe I suck at LoL and maybe I have a wrong perspective, but I've seen some P2W games and League is nowhere near it. Peace, over & out.