Take Algebraic Geometry, a field primarily concerned with the question "what are the zeroes of multivariate polynomial equations" e.g. x^2-y+z^3. Papers that could be considered part of the field were published as early as the 16th century but very little is worth reading from before the work of Alexander Groethendieck in the mid 20th century which really formalized the field in the form it is today. The vast improvement in abstractions meant old proofs could be rewritten in a much terser, easier to understand manner with the new machinery.
Similarly, now that we've solved the classification of finite simple groups[0] a lot of the deep expertise mathematicians had surrounding techniques to classify finite groups is no longer needed. A new researcher can learn a small, curated subset of these techniques and fully grasp the field. Since there's no more work to be done, there's no need to build deep intuitions.
More generally a lot of papers in mathematics are attempts to build the machinery to solve some bigger problem and most of those end up not being useful when the field cracks said problem. At which point, all those papers effectively get "trimmed away" since the result they were meant to support does not depend on them, and so no one need read them.
[0] https://en.wikipedia.org/wiki/Classification_of_finite_simpl...
The interesting thing though, is given free reign to prove whatever they want, they may go off and develop some entirely new field of mathematics and proving really deep stuff, but we just wouldn't recognize it as interesting. Like imagine if such an AI existed 200 years ago and invented Turing machines and proved P != NP, but it wasn't all that great at solving polynomials for whatever reason. We'd have probably thought it was all rubbish and threw it away.
This proof has a seriously low bus factor at the moment :scared:
There's 'understand', and 'believe you understand', and in other fields (say, software engineering...) you meet lots of people who think they understand, when they don't. I also think that in the SE case, because it's more 'relatable' ('look at my website') , people generally assume more easily that they understand when they don't.
Also if you look at theoretical comp sci results (calculability theory, etc) , or even complex software engineering systems (actual working distributed systems, etc) , I very much doubt that many people (apart from the people who designed and wrote them, and who may even be wrong about them! ) can _actually_ claim to understand them fully. You will understand, to some extent, the 'theorem' (ie the system), but the implementation will remain a black box.