Early game junglers have been rampant for high elos ever since S3, and it started all with lee(and Elise, the robin to his batman)
The jungle certainly is to impactfull, but it's nit just an enviromental issue. It's mostly to jungler design and Lee is the beginning of that.
He was the first to have literally everything one could wish from a jungle right there for the early game, all while still offereing some utillity later on. He might not be more than a syndrom by now, but he did set the jungle bar that exists till now: "You have to be atleast this busted early and still atleast that usefull later, or your not viable in high elo jungle"
And again, that's not an issue with the enviroment, it's an issue with the meta champs beeing balanced around that redicoulus Lee-bar. There's no reason a jungler should be fast clearing, well sustained, good dueling and yet have insane ganking preasure and some solid safety on top all at once, and yet that's what prettymuch every meta jungler has to offer to be viable(well, good dueling can be substituted with high safetyness, it just matters that you can invade without to much worries)
Even duering the cinderhulk meta, only Gragas and Seju were played in high elo jungle, because unlik other tanks they did have a dash for a reliable escape aswell as strong early clears and ganks.
Junglers need to be more focused on one thign early rather than good at everything. The guy that can invade me with low risk and probably destroy me 1v1 in my own jungle should not be allowed to powerfarm in between while excerting havey preasure on my lanes with his gank potential.
Given that jungle by default has a much higher impact early in the game than other positions, balanceing different junglers around a strong early vs other with a weak early and bad late does not worke, they all need differnt strengths and weaknesses IN THE EARLY already.