Modern Publishing
In the old days (when I started!) traditional publishing was controlled by gatekeepers. A lot of them were middle-aged men in tweed jackets. Or, indeed, middle-aged women in tweed jackets. These gatekeepers tended to commission works from writers in their own image for readers in their own image.
People who couldn’t get through the gate had to pay to have their books published. They were labeled vanity authors, which was an intentionally negative term. The idea was that these people were so vain that they wanted to shout about their own achievements … which the gatekeepers believed weren’t worth shouting about.
The funny thing is, the gatekeepers weren't born to their roles. They had no particular skills or knowledge. They were usually decent editors with an understanding of what people like them wanted to read.
The gatekeepers are still in place, though with less tweed and more cashmere. But the growth of self-publishing and hybrid publishing has changed the industry completely. Whereas vanity publishing was an exclusive pursuit that allowed the wealthy to aggrandize themselves, hybrid publishing and self-publishing are the opposite. They are highly democratic processes that allow authors at a whole range of price points to circumvent any gatekeepers and put their own knowledge into the public sphere.
It’s the author who identifies the audience, not a publisher. That means the author can write a book precisely tailored to what they know their audience needs. And they know their audience’s needs best.