Perhaps you're missing how the Greats are the only ones that are at this level? And that they also utterly curbstomp the rest of wulin?
Everyone with similar understanding in XAJH couldn't be curbstomped by LHC. Even CX was barely edged out by LHC and he's the weakest of the elite echelon in XAJH.
I don't even see how you can possibly come to the conclusion that the overall level of martial arts in XAJH is rather low when the situation is the same in LOCH/ROCH