Sure, it's possible to "learn" from LLMs in that they might spark some idea that you might not have thought of, but taking the output from LLMs as a source of knowledge is exactly what you shouldn't use an LLM for.
I understand this feeling, but it is important to push back against it, most importantly for the developer's own development. Not all ideas are good. I'd easily wager that most ideas are bad or at least not good, at least going from my own thought process. That is why we have places like HN, to share new ideas and get feedback. It is the best thing for the person with the idea (and also society) when their blatantly bad idea is responded to with generous, kind, informative, and direct criticism.
What was the subject and what prompt have you used when asking about the books?
(looks like parent comment has been edited; earlier it mentioned asking GPT for good book recommendations and getting made up results)
But when I ask an LLM to tell me something that I am an expert in, I am usually incredibly disappointed by the bullshit it spews.