By better understanding customer segments, you cater to their desires and sell more. Interaction designers use personas and marketers user personas to design better software.
There is no reason you can't Create personas to represent the groups you are writing to.
Most sites are created to meet the goals of an unidentified, unresearched generic visitor. The big mistake is believing customers are a big featureless blob called "the market."This is not just marketing text (though it’s that, too). It’s interface. This is text that can’t come from the PR department—it comes from us, the designers who are responsible for the user experience. The text is as much a part of the UI as the colors, the pixels, the stuff that designers are usually concerned with. Perhaps more.
-- A List Apart Calling All Designers: Learn to Write!
The Designer's Imaginary Friends -- Personas As a Creative Writing Exercise
You can't create elastic personas, bending and molding a fictional character simple to confirm the assumptions already made. Jeffrey Veen terms those personas unbacked by research "The designer's imaginary friends."
The first step in developing a persona is to understand you are not the user. And most personas fail right at this basic starting point. Otherwise persona development devolves into a creative writing exercise.
What was the system Taking the "You" Out of User refers to? Pyra and Blogger. Sometime you're just too close to what you're writing -- whether code or copy. Or even the code for a writer's tool like a blog.Not only were the personas not all like us—our personas wouldn’t even be able to use the system we were building for them! We’d been so blinded by our own self-interest we failed to realize we were building a useless team product.
-- Taking the "You" Out of User: My Experience Using Personas
Just being a blogger or copywriter makes you unlike most customers or users. You can use personas to write documentation for software, blog, write sales copy and more once you take the "you" out of user.
Persona Design for Content Strategy
Futher, personas are a primary step for developing content strategy. It gets you away from asking "what's the 'best' CMS software" when you have specific user types in mind.
Notice nobody ever asks "What's the best CMS for Journalists" ...or programmer management (called "Plogs"). That's because they'll make up fantasies about the user ....after the install.
And if you're a web developer who "doesn't write copy" then team up with a content developer who does. Sell the service as a value add to clients.