The point is not the fanout factor but the lack of limitations. A public post is such that anyone can see, without authentication. A widely shared post that req

The point is not the fanout factor but the lack of limitations. A public post is such that anyone can see, without authentication. A widely shared post that requires login to see is not public. An obscure pastebin paste is public, even though it's normally seen by a handful. But you don't get to control who these handful are.