Before ebooks, publishers made sense. They paid for the printing costs in exchange for a hefty percentage of the sale. Unless you had bags of money it was almost impossible to become a best selling author without a publisher.
The Internet, and ebooks turn that all around. Now the marginal cost of producing copy of a book is virtually zero. You don’t need a publisher to print and distribute your book. People can and do sell thousands and even hundreds of thousands of books on line without using a publisher.
If I was a publisher I’d be pretty worried.