A comment I read about Amazon, and which I'd never really thought about before, noted how books were actually the perfect entry point for Amazon becoming Amazon

A comment I read about Amazon, and which I'd never really thought about before, noted how books were actually the perfect entry point for Amazon becoming Amazon. The existing model was open to disruption, but more importantly the intrinsic attributes of a book itself made it perfect. Huge market, non-perishable, substitutable, easily shipped, similarly sized, with an incredibly long tail of varieties How many other goods fit those criteria?