From my understanding Diablo Immortal pissed people off because they wanted a new mainline entry and instead got a mobile game. Whereas LoL is just an ever changing MOBA game so it's not the same thing. At most fans might feel concern about the mobile game taking away resources from the main game, but that would be pretty misinformed considering Riots size and war chest. Then again, a lot of their players are kids so...distracting them with memes might have been for the best.