Lee Sin is essentially a bruiser that gets to act like an assassin. The conqueror changes have completely broken him, he outsustains most junglers that are not warwick and early on before warwick has armor he can even duel out warwick.
This is while having extreme safety from ward/ally/minion hopping that allows him to get out of any unfavorable situation.
And then the point and click stun that deletes 20%+ of someone's HP with insane AD scaling and that sets them up for a free easy to land Q for follow-up.
He's the very concept of overloaded.
Ekko and other assassin junglers are squishy. Lee Sin is not but he gets to build bruiser items and do the damage of an assassin while having their mobility too.