From the article it looks like he wants to maintain the "branding" of his blog so people recognise it as having a consistent quality - which I think is totally ridiculous as it's way too minimal to stand out. A good designer could clone the style in minutes. So what sets it apart? The way the editor promotes capturing ideas? This part isn't open to the public. Seems a bit odd.

It's working I suppose. And the "invite only" system sure helps drive desire.