As someone who can relate to the parent post, I will admit that if no one is actively listening to me then I absolutely will not speak. But I'm on the quieter side of personalities and don't enjoy talking for the hell of it.
The conversation analogy that xux made seems perfectly reasonable to me in that regard. However, it is (depending on the user, I suppose) not super "real-time" the way conversations are.
With Snapchat you aren't "creating" anything, just having casual conversations.