Thaks to big data, the cat's out of the bag. There is virtually no such thing as anonymous data in usable information. Only different degrees.
Anonymized medical data in Australia
https://www.zdnet.com/article/re-identification-possible-with-australian-de-identified-medicare-and-pbs-open-data/
De-anonymizing data in the 2012 presidential election: (long article, written back when deep analysis of people's voting habits was 'cool')
https://www.technologyreview.com/s/509026/how-obamas-team-used-big-data-to-rally-voters/
One brief excerpt:
Davidsen began negotiating to have research firms repackage their data in a form that would permit the campaign to access the individual histories without violating the cable providers’ privacy standards. Under a $350,000 deal she worked out with one company, Rentrak, the campaign provided a list of persuadable voters and their addresses, derived from its microtargeting models, and the company looked for them in the cable providers’ billing files. When a record matched, ÂRentrak would issue it a unique household ID that identified viewing data from a single set-top box but masked any personally identifiable information.
...campaign had created its own television ratings system, a kind of Nielsen in which the only viewers who mattered were those not yet fully committed to a presidential candidate
Anonymous just means that no-one has yet managed to link dataset A (Anonymous) with dataset B (Because we know who you are now)! Can you have useful data without it directly relating to reality and if it relates to reality in any specific sense then it can almost certainly be de-anonymised at some point once you have enough data to correlate with it.
... I also meant to say... I absolutely agree with you.