My point isn't that you can't win with renekton or hard carry with him. The point was that people who do so are doing so because of THEIR skill and THEIR outplays rather than because of the champion. Like I can play sona top in bronze as a smurf and make her look broken. But it doesn't mean she's good.
For the past 2+ years I've more or less been the king of low gold elo renekton. And I do it all while being 2v1'd, counterpicked, given 0 assistance from my team, and generally running ignite into an opponent who may or may not run a 2nd laning summoner. So yeah, I know all about winning with renekton even when everyone else abandons him as "unplayable" due to nerfs, bugs, etc.
But think about it this way... Imagine a meta where we slightly nerf crit, but make the average game time last 45 min or so. Now... what adc's are going to be the strongest? Vayne, kog, kai'sa. So imagine a meta like that where vayne has 48% winrate while other late game adc's and hell even a lot of mid game adc's sit at 51-55% winrate for games lasting 45 min or longer. Can you tell me vayne wouldn't deserve a buff or else the other adc's performing better than her deserve a nerf? Of course not... every adc would be saying to buff vayne if they play her even a little in that scenario. It's the same thing with renekton and the early game.
His scaling hasn't been buffed other than through itemization - which his counterparts can all also build and generally make about equal or even better use of. Yet he's completely lost the early game edge he used to have. Renekton with 0 kills isn't scary early compared to what he used to be. Sure if you manage to pick up a pair of kills early on - which requires outplay vs a scaling champ in a way that before wouldn't have required it... just you're renekton, you win - THEN he gets to where he used to be purely because he was renekton and it's early game. Then he is scary. And that's just my point. He's got too low a winrate considering he's theoretically still an early game lane bully champion in an early game meta. So either his early game advantage over more scaling champs needs to be restored, or he needs to be given more competitive scaling... because his scaling is still mostly crap. Oh you can make it work if you execute better than your opponent, but that's can be said of any champ. Like jax in a duel late game... he should win because he's jax and it's late game rather than only winning through outplay.