[Amezarak]

I found this very distressing and dispiriting when I read it was mostly used books from sources like BetterWorldBook. That undoubtedly means many rare books have been permanently destroyed, even some last remaining copies. The least they could do is release the dataset.

[Finnucane]

Rare and unique books usually end up at specialty dealers, not generic websites. But it is possible that some hard-to-get items could be lost, and there's no way to know without an inventory.