As someone who worked both for a small bookstore, specializing in rare OP books, and finders service, as well as two of the major (at the time) national book chains, Amazon certainly had an impact on how the book business works, in my eyes. Borders disappeared (not sure if any Waldens are around), one of the local BAM stores closed, another was shifted to a basically used bookstore, with lots of non-book offerings, and with trade in credit, as the small group of stores I worked for in the used and rare book business imploded, and several local used book stores disappeared. I was out of the business for some years before Amazon impacted both aspects of book retail, but I saw that coming. The internet, of which Amazon was the exemplar, was too big and efficient, opening to customers the wider world of used books, with one stop shopping, through Amaazon’s portal.
I finally went to using Amazon for my own used book needs, though I gritted my teeth. Functionally, it was a good idea, but I missed the local stores.