Using your activity as a substrate for ads has always been Google's business model, and never been a secret. You don't have to go along with it, but it's not a revelation.
You're right, and that's why I firewall off all apps by default so that they can't communicate out. I had granted an exception for Google Maps, accepting that I'll be supplying data to Google.
The revelation was that Google Maps was no longer just being used to collect data, but was being used to actively push ads outside of Maps itself. That was a bridge too far for me.
In the time since, I have rid my device of all Google applications, as Google's overall model is not something I can tolerate any more.
