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...
1M+ downloads for an app with licensed technology is noteworthy.
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?
[edit: spelling]
To be fair, however, I think we'd all agree that his accomplishments by that point were of a significantly higher caliber.