Keybase's view: identity on the Internet should not be just about Twitter, Facebook, and the other superpowers. Your membership to any site might be meaningful to other people, whether that membership is to something small like a phpBB forum about motorcycles, or something big like LinkedIn or Etsy. Often, the smaller the community, the more meaningful and close-knit membership is. And the more that community might want access to secure tools such as Keybase. If you're on the forum, you might _really_ need to reach out to another user of that forum, securely.
It might be a good time to mention that Keybase is looking to hire an Identity Evangelist[1]. This would be someone with a tech background (i.e., from the HN crowd), who has great presentation skills and experience, and who wants to help other sites and apps integrate with Keybase.