I had this exact same experience and conversation with my local librarian as a kid. Rpg books I checked out would get stolen after a while until none were left that could even be borrowed from inter library transfer.

Long article but there’s a short answer. That second theory is not a myth. Libraries where I grew up (Bay Area, Silicon Valley) used to stock almost a complete set of AD&D but they kept getting stolen in the 80’s and 90’s. So they stopped buying new stock (a librarian told me) and eventually a dozen libraries in the…