Keep in mind that every single logged-in user has their own blog, whether they use it or not, whether anyone reads it or not. So, theoretically, "an average of

Keep in mind that every single logged-in user has their own blog, whether they use it or not, whether anyone reads it or not. So, theoretically, "an average of one visitor per blog" would also be entirely consistent with "every single Tumblr view represents an active Tumblr user", because the number of people who visit Tumblr would thereby equal the number of blogs.