But they aren't more successful. They can solve this because of standing on a huge body of work made by working mathematicians. Without it AI would get nowhere. Now AI are burning the minds that fed it for short term gain.
Insight in mathematics doesn't emerge from brute-forcing conjectures. There is a recognized aesthetic economy that exists and without a semantic filter to detect the significance in any of these proofs we just end up with a lot of noise.
Yes, it would be very much like automatically generated tests. These are not worth much by themselves, but in massive bulk they can do interesting things.