It's the reason why I can search for "prefecture Melun" on my laptop, then jump in the car, open up maps on my phone, Start typing "1" and watch it suggest "12 rue de Gambas, Melun 77320", which happens to be the address of the Melun prefecture.
That sort of thing happens for me every day, and i think it's kinda cool. Google knows this stuff about my life and will suggest it at useful times. If I open maps on the day I have a flight, ferry, or hotel reservation, it'll just assume I want to navigate there (because it read one of my emails) and suggest it for me.
So yeah, I guess I should be outraged and worry that they'll start targeting me for ads or ratting me out to the NSA or something. But thus far they haven't.
It's just that they can offer all this cool stuff if they connect your devices. And in 2018 that involves using a database. Personally, that does not concern me all that much.