[DavidW]

Can you imagine the scandal it would cause if Google were putting this data out there as accurate and then it turned out not to be? What kind of damage might that do to their reputation?

Put yourself in Google's shoes. They are an advertising agency with a search engine. Their profits come from the people who advertise so what happens if they tell those people 'Hey< we're going to give you this great data so you can make better advertising decisions' and then it turns out that the data isn't even accurate. Advertisers would be suspicious of what was next.

All the paid tools out there have reason to be concerned. They've all thrived because these numbers weren't available until now. Of course some of their owners are going to try and spread a little uncertainty.