General Discussion

Also, there are many varieties of non-fiction: history, auto-biography, engineering textbooks, philosophical analysis of gender rights, cookbooks, self-help, ....

Plus, extending what you say, the lived experience of a human being can be mocked up, simulated, assembled from fragments by an AI, but it would not have the true feeling or perspective or real experience of a human.

However, with fact-checking and data in hand, an author can have perhaps deeper or broader insights and feel more confident in the data they are using.

But a careless author would just accept AI "fact-checks" without checking themselves. If it were me, I'd want an AI that says stuff like "The proportion of college graduates on page 129 is not accurate: see in World Bank site." Then I'd go check myself.

An uninspired author would copy-paste large sections of writing in whether or not the "insights" are garbage or bogus or a misinterpretation. But it was ever thus.

Ultimately the true test will be whether the author can talk knowledgeably about the contents. I imagine an interview going "In your third chapter you make the startling claim that supporters of Finnish indigenous people have antlers growing from their shoulders and elbows. Where did you observe that?" ... pause ... "umm, er".

Especially if editors are AIs or are useless without AIs.