I think the issue with Jhin isn't his damage, it's how his spells work with no clear "max this first
Sure you could say you max Q for better wave clear or poke, but someone else will tell you that's a bad idea and maxing W first for a better root and damage is better.
His E is usually maxed last but I have seen players max it second which leaves either the Q useless until late game or the W to just do a quick snare with low damage.
I believe his Q should be maxed first but after playing some games with maxing W first, the W rush was a lot better in ganks and damage.
Do you guys feel the same?
and so forth.