Most of the comments are focused on the author's trivial mistake (when was this information surfaced: now, or at launch?). His substantive point is more valuable to bring to light. Perhaps the fact that there are top-users lists highlights the tension between what Snapchat says that people use it for (sharing brief moments with friends) vs what people actually use it for. In fact, I actually use Snapchat for sharing…
Even if Snapchat isn't making a big network diagram it's certainly possible to create one.