Sinister- Like I said, Lee's stacked kit is balanced by requiring a higher level of mechanical proficiency to use and also not scaling. Champs like Kayle get a ton of utility whilst being strong at all stages of the game.
Lack of scaling doesn't define a kit and yasuo similarly requires mechanical proficiency to make the most use out of his kit due to the way his dash is designed.
Also, Lee sin scales really well, he just switched from assassin to tanky dps/support.
I never said he wasn't good, or that he wasn't top 3 in terms of junglers. Also tanks like Naut and Rammus have amazing ganks pre6. I play Naut a lot and I'd say he's probably top 5 in the game in terms of pre6 ganks if you know how to manage your CC properly. He can gank at 3 (or even 2 with red buff if you like to roll the dice) and by the time you've ganked your smite will be up for your next camp. I try to circumvent the slow clear issue by only farming when my smite is up, and trying to do something else when it's down (eg. gank or ward). This is only efficient on champs like Naut though, who is a good ganker without his ult and isn't as gold-dependent as most carry junglers.
Just to clarify, I know that bruiser junglers like Lee are generally better than tanks, because they have a similar level of gank potency but also do a ton more damage. I'm just saying that I don't thik Lee is cancerous. You can still do well with tanks if you play to their strengths. Tank junglers have won tons of games against Lees and the like at the highest levels of play.
Rammus is a bit of an exception given that his gank potential is based on leveling up his taunt, he doesn't gain a super CC at 6. Also teleport/homeguard cheese. Nautilus, really isn't, if they're playing super overextended he can but because his damage contribution is really low, the enemy laner goes down really slowly. This leaves you open to counterganks and because lee contributes a lot more damage if you get counterganked you lose the 2v2 flat out. His gank paths pre-6 are also a lot more predictable and easy to ward against.
His 6 gives him a targeted powerful CC which substantially opens up what conditions in a lane he can gank from, plus is a massive amount of knockup and actually gives damage negation.
The only way what you're suggesting works is if laners routinely super overextend, otherwise you'll get super punished in terms of pressure for your super late leveling, because while they're not gold dependent, tank junglers are quite level dependent, as in it's important to their CC and durability.
Yes they have, but no setup is 100%, there are countermeasures but they generally involve your team being better coordinated and stronger in the earlygame. That said at the highest levels of play tank junglers beat lee less now then before, because the jungle itemization changed to favor bruiser junglers and the jungle itself is more valuable and is less dangerous.