Couldn't find a discussion yet on Wikipedia about how slop books with ISBNs and publishers are more authoritative sources than primary sources by the letter of its rules, but I expect there'll be one by the time I finish popping a bag of popcorn

Unsurprisingly, Wikipedia does not take this position, and is in fact pretty skeptical of self-published and especially AI-generated work. Its guidelines do say that "books published by respected publishing houses" are more likely to be reliable sources, but that's obviously different from having an ISBN, and of course such books are not AI-generated.

The primary sources thing is a different matter; primary and secondary sources serve different purposes.

Brave search is returning secondary sources, not primary sources, for several serious real life topics in the last weeks it seems.. I mean Law and Medicine.. what is that about?