Yahoo didn't buy the technology, they purchased the talent. Talent that knows how to reach an audience. You can always get high quality engineers to figure out the rest...
The article's main point is that the founders didn't do anything really noteworthy, technologically speaking, and so Yahoo overpaid for the talent in question.
A million downloads of a free app is not really that noteworthy. My friend made a simple, free iPhone game in a weekend where you tap on a soccer ball and keep it from dropping and routinely gets 10s of thousands of downloads a month with absolutely no marketing.
I have some rather strong misgivings when purchased talent != high quality engineers where software product/company acquisitions are concerned.
There are some excellent professionals out there with a far more rigorously proven and solid track record of knowing how to reach an audience. You're suggesting the 17-yr-old & 2 compatriots have proven themselves to possess $30-million-worth of reaching-an-audience skill?
Which is why this acquisition was more about PR than talent or technology. It says (or tries to say), "You might think we're just dusty old Yahoo!, but we're hiring 17-year-old wunderkind too! We're hip to the next big thing! And remember we have a new CEO..."