11 for poking
12 for mixups
f2 for pressure
f3 for wiffpunish
b2 for oh
b3 for low and lowcrush (it does lowcrush, yes)
d1 interrupt
d12 for mindgames
d4 for footsies
3 for punishment
etc etc
most of that require hitconfirming. Nvm inputs like bf2d, dbf2b(wrestler) etc that are all over the place. If you think its easy you're fighting common sense here. Quad and instant pound is also hard btw, whether you argue it or not its a fact everyone will agree on.
And just compare him to everyone else
Johhny f3 for everything. d4 occasional poke/highcrush
Dvorah - see johhny
Kano - f2 for everything, d4 poke, b2,b3 for mixup
Kotal - b1 for everything, d1 fast poke, f1 wiffpunisher.
Jason - b1, b3, d1
and so on
Difficulty will make you drop things sometimes. Its just how it works. its easier to input db2 than bf2d. its easier to know range of 2 moves rather than 5 moves. Its easier to hitconfirm one move, than 5 moves etc. And no matter what you say or do you have more chance to drop confirm, combo or make a bad decision with Jax, than, say, Alien. So no matter how pro you think you are if you ever been to top8 at major you know difficulty IS a factor. Jupiter quit MK because he dropped crucial combo at evo for instance. As well as dropped combo cost him a spot in ESL finals.
And its not just difficulty but also time. Jax takes more time and does not offer particular advantage. So any top player will decide to use this time more effectively. Of course everyone can play Jax like you described but that wont get you far in tournaments.