This has been a problem practically since the beginning, but it wasn't nearly this terrible, and it's only escalated since they've been focusing so much into their precious esports. I don't mind them wanting to make the game popular, but it wasn't tv shows & internet streams that made the game popular in the first place. It was because it was felt fair & balanced, and when some champion was noticeably under performing or clearly abusive, they quickly brought them into line; within a couple weeks, not several months, and it was where it counted in the champion kit to prevent them from drifting into that direction again. There were a few exceptions that took longer, but the point is riot didn't play favorites & they didn't drag their feet about it. This is primarily what kept it fun, that they payed attention to the community to see what was fair; and it's how they grew up so fast to begin with.
Any old time gamer here can tell you, the toxicity of the community has significantly increased as they started trying to shove the game as a televised competitive sport. The 'strategic diversity' & 'counter-play' were blatant lies to calm the masses from long outstanding frustrating gameplay; looking at the numbers through out the patch notes shows it clearly. The favoritism for abusive champions getting noticeable compensation whenever they get any nerf, yet the more fair ones only get a slight positive tweak if any. Not to mention the repeated hand-waves for the game not going downhill; despite the obvious one sided balancing act and blind eye to the venomous parts of the population (tribunal was never updated & outright replaced by an inefficient bot).
In the past few years, I've hardly played 1/10th what I used to the year it came out. Tired of the game as a concept in general? Not really, I've still got a handful of games well over a decade old I still play for having good gameplay & stories. It's clearly not the game it used to be, whether another company had a hand in it or not, I'm unsure; but I'm betting, that if they don't get their act together to start fixing it with the community, it'll fall apart in humiliation.