I think the point is that you write your content in Markdown, the structure of your site in JSON, and this generates and serve HTML with a decent CSS. Interesting for programmers who want to quickly publish content without bothering with presentation. It's like Jekyll or Nanoc for busy (or lazy) people.
It would help if the site mentioned this. It reminds me of an old analysis of the Mozilla website where, upon launching, it showed a full screenview that preached the gospel of Open Source Software to the visitor instead of providing the user with a link to the Firefox browser.
You have to provide some context to visitors, like maybe those who are not coming from HN.
