I find this claim very surprising.Saying that "there is no new profound number theory" implies a deep understanding of the totality of Mochizuki's work, which as far as I know is so complex and far from the current state of the art that nobody really understands it yet.
Mochizuki's work may prove to be right, and it may prove to be wrong. But saying there is no new profound number theory at this point seems a little premature.
I cannot really give a complete explanation, being unfamiliar with his papers. But to argue by analogy, suppose I had invented a difficult and programming language. How might I persuade you to learn it? One way would be to use it to solve problems that are known to be difficult very easily, elegantly, or extensibly.
It is the same with "inter-universal geometry". One should not have to follow Mochizuki's work all the way through his proof of ABC to know whether it is good for anything. What is the quickest route to a surprise? What can Mochizuki now do with less effort than the existing experts?
The absence of good answers is behind skepticism of the proof.
Mathematicians, and especially the very best mathematicians, are very eager to learn. I don't know of any great mathematician who demonstrates a "lack of intellectual curiosity".
That said, there is much more mathematics available than anyone has time to read. It can easily take an hour a page, or more, to read a dense research paper. Mathematicians, like everyone else, have to be selective about what they choose to learn.
It is very rare for great work to be ignored, but here is one example:
Take the Fermat-Wiles proof. It's probably the most significant number theory result of the last century, yet it doesn't contain new profound number theory. Its genius is the use of elliptic curves, which is algebraic geometry.
I'm not saying Mochizuki's proof doesn't contain new profound number theory, but this is a very possible outcome, we just don't know yet.