That's a good point. Put another way, were I to run a local copy of a wikipedia mirror, right here in my own bedroom, I'd be putting myself eye-to-eye with any wikipedia employee or volunteer. I'd have the same tools in my hands, as they do. I'd be one person, a PHP script hosted by an apache process, and the wikipedia data set.
But, contrast that to Facebook, and the concept becomes more interesting. Facebook's search utilities are similarly unsatisfying, despite the massive resources of the company. This is probably not a blind spot, but more about the level of quality provided, for free-tier, unprivileged user utilities. Advertisers probably gain better reach, but perhaps without knowing exactly who they reach. Facebook's search tool can't be used to discern the capabilities or qualities of one or more of the indices Facebook uses to negotiate the landscape of their data.
But, contrast that to Facebook, and the concept becomes more interesting. Facebook's search utilities are similarly unsatisfying, despite the massive resources of the company. This is probably not a blind spot, but more about the level of quality provided, for free-tier, unprivileged user utilities. Advertisers probably gain better reach, but perhaps without knowing exactly who they reach. Facebook's search tool can't be used to discern the capabilities or qualities of one or more of the indices Facebook uses to negotiate the landscape of their data.