You want to know the real reason Rito doesn't nerf Lee Sin?
They're scared!!!
If you can recall in about the middle of last season Riot had a nerf/rework on the PBE's for Lee Sin, and honestly I liked it and thought it was more balanced. Can't remember everything about it but essentially his mobility was reduced, his base stats were reduced, his execution damage was reduced, but his ratios were increase slightly, and his sustain was increased to make up for the lower base stats. Something about his dash was also changed, can't remember what exactly but it was definitely a nerf.
That's what I remember at least, I could have missed something or got another wrong but I'm pretty sure that's the gist of it.
So what happened to this plan? The Lee Sin community on the old forums went into such a ridiculous uproar that Riot scrapped the whole thing and said "he no longer gets a shield when dashing to a ward" and that was it! The Lee community literally cried Riot into submission on this one, stuff about his "identity being ruined."
The truth is they balanced him, which ofc has to be mainly a nerf since he's so freakin strong atm, so the multitude of people who play him got upset like anyone does on the forums and the rework was cancelled, and anytime Riot wants to try balancing him again they'll have to deal with the tidal wave of tears they know they will receive, just like last time.
That being said I'd rather see just J4 and Vi nerfed slightly while buffing the other junglers instead of nerfing Lee. He is kind of OP due to his early game but he's not the most serious offender atm... cough J4 and Vi* cough*.... so I don't think nerfing him is the answer atm. Was just saying why he won't get nerfed for a very long time is all.