Dave isn't giving you a solution. He's pointing out a number of problems that need to be solved. Just because technology works fine doesn't mean it's the optimal solution. Tech develops incrementally.

Stack Overflow has a search feature and it works fine. But wouldn't it be cool if someone aggregated results from different programming websites? (http://news.ycombinator.com/item?id=1854731)

Check out Union Square Venture's blogpost from May: http://www.unionsquareventures.com/2010/05/stackoverflow.php. In addition to describing their investment, the post describes problems in the space. If you had never heard of Stack Overflow and you only read about the problems in that post, would you say the solution was too complex?