Because "bigger = better" does not work for highly specialized expertise, where the knowledge is not available on the public Web. It is naive to believe it's all open out there merely because the Web is large and we have Wikipedia.

If you are a highly specialized professional intellectual property paralegal, a forensic tax investigator or a post-market pharmacovigilance analyst, you will need for-profit knowledge sources, and your answers will often require synthesizing and interpreting multiple sources.