[QUESTION] What prevents Steemit from having its own Market for selling products instead of just exchanging them for other crypto?

I noticed @mericanhomestead sells products through his site and there is the option to pay with SBD. Is there a reason more users don't do that?

It doesn't have to be physical goods. Someone could be selling digital versions of his books or programs he wrote. Yes, they can be pirated afterwards and there is nothing you can do about it, but it is an option for making SBD more than just something you hoard or exchange.

For example, I have a book on Amazon. This one: https://www.amazon.com/dp/1549878581
You see that ridiculously high price of 15$? I don't make 15$ every time someone buys it. I make 4$. The book is 150K words and I paid money for a subpar proofread. I am currently 800$ in the red for a book that is "supposed" to be free of charge to publish and still looks too expensive for most to buy. What if I make an post / ad where I sell the PDF for 1 SBD and send it via email to the buyer? What prevents me from doing that?

So my question is why aren't there people making posts about selling goods for SBD, and instead spend 90% of the posts in talking about it? Wouldn't that give the crypto and Steemit in general the proof they need for why this model works?