Yes, it goes on. As it is now very easy for writers to publish their one material why should they wait for a traditional publisher to accept their work and then take several months to get it out into the open?
The traditional publisher has to be confident enough about your work to risk time and money on various services you might want to buy in as a self-publisher:
· Cover design
· Editing (structural)
· Editing (line)
· Editing (copy)
· Book design
The publisher will have to sell several hundred books to get their money back on those upfront / overhead costs. Whether the book sells twenty or twenty thousand copies those prices remain the same.