The reason the Romans were so weirdly stingy when it came to books is because they were a bitch to make and expensive as hell so unless it happened to be in a library you had to find someone with a specific book in their collection. It wouldn’t be until the early medieval period when scriptoriums started to appear that you see large numbers of books being reproduced for relatively cheaply.

Oh also if a book wasn’t well liked or just wasn’t copied frequently then it had a pretty good chance of being lost. This is how the works on the Etruscans by Augustus was lost, note it was multiple volumes yet I’m pretty sure we have none, from what citations still exist is seems to have been a proper historical and anthropological work.