I think that libraries typically stock in accordance with demand and costs, not merit

I think at this point in history, libraries are irrelevant. In the far past, books etc. were expensie and libraries kept whatever they could get. They were, collectively, the waybackmachine.org of the world. More recently, they would buy what their customers might find most useful for research. A collection of books and especially years and years of journal subscriptions. These would be local copies, with no real archival purpose in holding these, these would always be available somewhere else. Now, I don't know what they do. I have gotten a few books from university libraries in the last few years, so they served to save me some money and/or allow me to read things I wouldn't have spent the money on.