It has to do with priorities: who gets what and how much.

Self-published bestseller Hugh Howie spells it out from one to ten in this article — including some history — and rates the importance of the different “stakeholders” thus:

1: Readers
2: Writers
3: Editors
4: Bookstores (digital only)
5: Libraries
6: Books (as in paper books)
7: Narrators
8: Cover artists
9: Publishers
10: Critics

The priorities part comes in when you swap “author” for “publisher.” A partial list might look something like this:

1. Bookstores (physical)

2. Libraries

3. Books (as in paper books)

4. Critics

5. Cover artists

6. Editors

7. Narrators

8. Authors

9. Readers