Well, you don't need to think too hard about this when sites like archive.org are in legal danger, and the dream of Google Books is dead. I had not considered the "everything on the Internet is AI/SEO slop now" - that's a good point too: even if the stuff exists online, it's often almost impossible to find.

A few months ago I half-remembered a quote from a famous philosopher. Google and Bing returned only the vaguest, most useless search results - basically assuming I didn't actually want the quote, but general information about the philosopher. So then I turned to ChatGPT, which asserted that no such quote existed, but here were ones "like it" (they weren't.) Finally I skimmed through all the books I had until I located it.