Comment by const_cast

> anonymised product analytics?

They're not anonymous, they're just pseudo-anonymous. It's incredibly easy to collect pieces of data A thru Z that, on their own, are anonymous but, all together, are not. It's also incredibly easy to collect data that you think is generic but is actually not.

Do you query the screen size? I have bad news for you. But, all of this is besides the point: when that data is exfiltrated to a third-party service, you have no idea how it's being used. You have a piece of paper, if you're lucky, telling you the privacy policy, which is usually "you have no privacy dumbass".

Even if data appears completely anonymous to humans, it can be ingested by machine learning algorithms that can spot patterns and de-anonymize the data.

I mean, we have companies who's entire business model is "how do we string together bits of data and tie it to real-world identity?": namely Google. Turns out it's remarkably easy when you have your hands in a lot of different pots. Collect a little anonymous data here, a little there, and boom: now you know that Billy Joe who lives on First Street loves to go to Walmart at 1 AM and buy Ben and Jerry's ice cream in a moment of weakness.