Not just exposure, but exposure to the right two communities: many designers follow them, and many coders. These groups tend not to hang out (like biz and coder guys don't...). If there aren't any other intersections, it's a unique competitive advantage.

Perhaps the trick is also in knowing what you got; and what problems others have got.

hmmm... I do wonder if some kind of specific advertising like this was a thought very early on for them when they started dedicating themselves to blogging, speaking to build an audience, as a financial rationalization of what they wanted to do anyway. :-)