This review implies that the main use case of microfilm transfer was to free up shelf space by destroying books and putting them on microfilm. To my knowledge,

This review implies that the main use case of microfilm transfer was to free up shelf space by destroying books and putting them on microfilm. To my knowledge, that is not the case: the main use case was for periodicals like newspapers, magazines, and journals, not books. And certainly, microfilm was not intended to free up shelf space in the library: most items in a library's collection aren't on the shelves, they're stored in warehouses and basements. Paying to store miles of old newspapers was not sustainable for most library systems, and despite what this review implies, newsprint does not last forever. The alternative to microfilm was not that we would have pristine copies of our history easily accessible to every library patron, it was that most copies of a periodical would simply be destroyed. The remit of public libraries is not to preserve books, but to provide access to information. There's a crucial difference. Microfilm was not ideal, but in a pre-digitization world it was about the best option available to provide access to those old periodicals that would otherwise have been lost, or at least hard to access.