you and i have a different version of free to play, free to play in my world means that everything is free. if the micro transactions do not affect gameplay at all, then and only then is the game free (i.e. Brawlhalla on Steam).
LoL is PAY TO WIN or GRIND TO WIN (runes/rune pages). this ultimatum is designed to do TWO things, it allows Riot to call the game "free to play" it also generates revenue because people who have money to spend and do not want to GRIND TO WIN may instead PAY TO WIN.
this is fact. perhaps most players do grind to win and support riot by buying skins. i myself bought a Commando Garen skin for URF years ago. i then vowed to never buy RP again until URF was a permanent gamemode.
the only reason i would pay for URF is to support riots maintenance of URF. it IS ALSO MORE OF A BRIBE AT THIS POINT. becuase ppl vote down posts that say make URF permanent.