[sah2ed]

The best data set will in general only be as good as the raw data that was used to prepare it.

I think you underestimate just how far along Google is with respect to the huge amounts of raw data they handle. They've been around for 20 years now and amassed a lot of expertise handling all kinds of data imaginable at scale.

If you disagree, who would you say is ahead of Google wrt general data sets that are valuable?