The article talks about private, public, and commercial voices as if they're discrete things, but it seems more like a spectrum to me. For instance, my zine is ostensibly commercial (compellingsciencefiction.com) but I have specific goals about the kinds of stories I want to get people reading, which limits my audience pretty drastically. I think in most true commercial ventures businesses adapt their products to find a market (which makes money) rather than try to adapt the market to their product (which is harder and makes much less money). This is just one example of a point on the spectrum of private-to-commercial.