The n turns out to be 35. Or 36. (link) Thirty-six tweets to contain a message that you want to write. This is such a deliberate fight with the medium that is unsuited for long-form, richly formatted, well-argued texts.
The driving factor here, of course, is reach. She is not content with talking to herself and a handful of followers — she wants to broadcast her speech to as many people as possible; hence Twitter.