I also think if you are at the “don’t know what you don’t know” point of learning a topic it’s very hard to direct an AI to generate comprehensive learning material.
The main advantage of LLMs is that you can ask specific questions about things that confuse you, which makes iterating to a correct mental model much faster. It's like having your own personal tutor at your beck and call. Good guidebooks attempt to do this statically... anticipate questions and confusions at the right points, and it's a great skill to do this well. But it's still not the same as full interactivity.
When it’s just a book. I find myself having questions like you mentioned. When it’s just LLMs I feel like I don’t have any structure for my mind to hold on to.
I also feel like there is an art to picking the right order to approach learning a topic, which authors are better at than LLMs.
A good book by an expert is still better than LLMs at providing high-level priorities, a roadmap for new territory, and an introduction to the way practitioners think about their subject (though for many subjects LLMs are pretty good at this too). But the LLMs boost a book's effectiveness by being your individualized tutor.
Altho maybe I'm stretching the analogy too far.
I remember fumbling around for ages when I first started coding trying to work out how to save data from my programs. Obviously I wanted a file but 13 year old me took a surprisingly long time to work that out.
Almost impossible to imagine with AI on hand but we will see more slop-merchants.
I have found that asking AI "You are an expert teacher in X. I'd like to learn about X, where should I start?" is actually wildly effective.
How will LLMs be trained if no humans are making learning materials?
If you didn't, then you won't be included the training set (obviously) and the AI would not easily know about you. Sort of how if you start a really cool company but don't make a website Google doesn't know about you and can't return you in their search results. It's valuable for Google (AI) to know about you, so it's valuable to build the sites (docs) to get indexed (trained on).