Google, Tumblr, etc. all have investors and shareholders which are trying to turn a profit. I think the idea here (and Garry can correct me if I'm wrong) is that they'll never take on outside funding or entertain selling the company, the sole purpose of the site will be to build something that is sustainable and lasting as opposed focusing on profit.
That's exactly why $5 doesn't seem like a transparent deal right now. It is also not clear who is the target audience here. The average person who would sign-up for a blog, wouldn't shell out $5 so easily, and a professional blogger would look at it suspiciously to begin with (given the extremely early stage). It would be better if that reference to $5 is clarified in-depth, or taken out altogether with a different kind of explanation.
