[elzbardico]

Let's remember that Gmail opened the door for Google to become the default identity provider for many people. A lot of consumer and behavioral data can be inferred from every service account tied via OAuth to google.

Were you searching for homes to buy? You'll probably use your google account. Bought a couple of home automation devices, cameras, and doorbells? Chances are you are using a google login.

Use Waze in your car? Now google knows what car you drive and the places where you go and can tie it nicely with all other pieces of data because you are using your google account.

This is invaluable for them. From your usage of a google account, they can infer your family arrangements, probably what your job is, your income and wealth level, tastes and habits.