It has been the main selling platform for indie authors, so I suppose you could call it a publisher. For those writers getting an alternative would be good because Amazon does have a bad tendency to both kick out authors who write stuff they don't approve of, as well as bury authors they don't like but are still willing to let keep their books on the platform with their programming, making certain authors and certain type of books a lot harder to find.

But losing Amazon would still bring problems to indie authors as a group as the book buying audience has gotten too used to it, it would take them time to find the authors they are already familiar with and buying from other platforms. Or even just finding those new platforms.

And indies are where the male, and conservative authors have moved to after the trad publishing stopped buying their books.