Shaco is heavily reliant on snowballing early game, either himself or his teammates As all he brings to the table is (mostly) damage, and his boxes don't scale in health and have to be pre-placed in the late game. Shaco excels at ganking, and eventually assassination come teamfighting. If he doesn't get the gold recquired of him to pop the squishies, then he isn't doing his job.
I'm not really going to argue too much on Shaco because I do think he is the most borderline of the champions I listed anyway. My basic rational for listing him is that if he were ever buffed to the point where he was a competitive champ he'd have a playstyle which would revolve around crushing enemy junglers out of the game before they ever had a chance to respond. This is the degenerate and low counterplay style which I believe defines most competitive junglers right now.
Lee excels as an early game duelist, being beaten out by only a few champions. Once he hits 6, his ganks can become devestating to the enemy team IF pulled off correctly.
Skill is a non-factor in competitive play. The players we are talking about are skilled enough to learn any champ and all of the tricks they need to play them properly. Therefor Lee is an excellent dullest with insane post 6 ganks in pro play.
However, unless the game ends quickly OR your team becomes fed, Lee sin loses a lot of his power. Were he to build full damage, he would rarely kill a target and get out in a team fight, even with his built in escapes. That's why most lee's build bruiser, to survive the dive.
The exact same logic is applicable to Elise and Rek'sai. They both crush early and transition into tankier fighters late game.
Much like Shaco, if you have vision on lee, he loses out on a lot of his power. Late game, he is literally an insec machine with good chase potential, but he cant dive headfirst into a fight and get off sustained damage, nor survive it long enough come late game.
I don't understand what your argument here is to be honest. Lee 100% has the same degenerate playstyle as Rek'sai and Elise. He starts the game absurdly powerful, capable of dueling and invading weaker junglers. Then he builds tankier into the late game to abuse the strong utility and high bases on his kit. Stop me if this sounds familiar.
What all the others (minus assassins) have is sustained damage, tankiness, and strong CC, with equally strong clear times and ganking potential.
I must have missed the part where Elise and Nidalee are tanky, or where Nid has strong CC, or even where Gragas has strong sustained damage.
What these junglers share is strong early games that they use to suppress any other jungler who might otherwise see play. This is specifically why I did not list Graves or Kindred, I do not believe that they fall into this pattern in the same way as the other jungles I listed, even if they are stronger than the majority. I was also iffy about Gragas for a similar reason.
I believe Graves and Kindred have major problems, but I don't think they are the same as this group.