This is very near and dear to my heart.
We are talking about “teaching” and I doubt anyone who supports the current education status quo is advocating to teach using unsolved problems.
That said, I do feel, personally, and have long advocated for, teaching using unsolved problems as a better technique, because you learn strategies for approaching a problem much better than: here’s theorem 13.4 heres an exercise problem that uses the theorem, what’s the answer?
It reads like you see my opinions are black and white and yours as spectra.
Using your own reading on your own comment the logical conclusion is “a system that teaches to an answer will be unable to answer unanswered questions because the students were only taught to answer questions that already have answers.”
A great example of the answer being the most useless part of one’s own personal knowledge is Timothy Gowers YouTube content:
https://m.youtube.com/watch?v=byjhpzEoXFs
But who’s cares what some YouTuber is up to? He’s just out here promoting an inherently incorrect education method wrought from a dysfunctional mind.