It's the reason why I Indie-publish. Once my books became profitable I stopped worrying about getting an agent or publisher. And I see a lot more of successful indie-publishers then getting picked by the big publishers.
And some publishers/agents want sales numbers for books, so Steem would be difficult to calculate into that.
But I use Steemit as a revenue source for my books. I quickly learned if I serialize a book on Steemit, the book becomes profitable before it even hits Amazon.
But in terms of an audience, that doesn't just occur in books, but also music. And there reaches a point, if I have developed a large following on my own, what do I need an agent or publisher for?