I honestly don't understand the point of a "walled garden" blog, aside from perhaps a curation mechanic. If I were to post on there among all the great writers on the site, still nobody would have seen my work. So rather than I still a sense of inferiority into, well, everyone, why not just make it open and feature the best writers? Win-win. And if I'm not mistaken, that's Medium's approach, is it not?