For example, Amanda Hocking -- who's become moderately famous in Internet and publishing circles over the last few months for a meteoric increase in her sales as a self-publisher of e-books -- has just signed a deal with St. Martin's Press for a four-book series. The terms haven't been released, since they rarely are, but reports indicate that the price was over $2 million.
And, yes, Hocking could have made $2 million selling those books directly -- possibly even more quickly than she'll make it in the SMP deal. So why did she do it?
“I want to be a writer,” she said. “I do not want to spend 40 hours a week handling e-mails, formatting covers, finding editors, etc. Right now, being me is a full-time corporation.”Publishing is a job -- no, more than that, it's about half-a-dozen jobs, with editing, marketing, production, sales, cover design, and so on. There are people who are good at all of those things, I'm sure. But are they equally good at all of them? Better than the people they could get to do those jobs?
The "Big Six" have spent the last few decades getting really good at one thing: getting lots of copies of books  in front of a wide audience. So, if you're someone who already has a wide audience, it might seem counter-intuitive to go that route -- you've already got those people, right? But those publishers have been changing name recognition into book sales since Henry Ford's Own Story; they've got a reach and scope that no single person can match.
Or, to put it a different way: the Internet did not magically erase the advances of the detailed division of labor; it's nearly always better to specialize. And what writers specialize in is writing.
 Replace "books" with "content" if you want to be trendy; a book is just a container for a variable quantity of "content."