> I don’t have the same thing for the ebooks I’ve read, and it gives me a weird feeling of amnesia.

I have a similar feeling when it comes to my music collection, some of which includes rare recordings. I ripped everything and have it at my fingertips on my phone, computer, etc, but I often find that I’ve forgotten when I have. When I was younger, I kept it all on a shelf. Browsing one’s music collection (or a friend’s) was always a pleasant way to spend an evening socializing. With apps, that is all gone. I have recurring fantasies about building some kind of physical music player, with cartridges that one could insert into a “player”. The actual music would be stored centrally, but this would be more like a mnemonic device to make browsing more enjoyable. I could imagine a similar thing for ebooks.