I have always been against the very idea of private posts, since that gives the false feeling of privacy. Nothing you post on the Internet is private (or, rather, stays that way for a long enough period of time), because there’s no way you can enforce that privacy. Hacks, leaks, and security flows aside, your private post staying private very much depends on the good will of those you shared it with (i.e. not taking a screenshot and posting it to reddit or elsewhere — you’ve got the drift). Your brilliant idea of private elements could, on one hand, have just made me reconsider my position. It does indeed sound cool. On the other hand, however, the more seamless it is (and seamless is what’s actually cool about it), the more prone private information in your post is to inadvertently be made public by the readers who didn’t understand that some parts of what they were seeing was for their eyes only.