[atmosx]

I see a lot of concern around privacy and that’s a blessing.

Honest question: Let’s assume for a moment that google wants to do something evil, what kind of info will “providing a mobile number” give to google that the email, searches, possibly DNS queries, oauth2 authentication and browsing tracker will not?

[ken]

Phone number is a universal ID whose transmission and content is managed by another company. It's one which we generally make public, too (that's the point). Plus, unlike email, it's difficult and/or non-free to create more, or manage several of them.

A malicious Google with my phone number could easily sell my web searches to the phone company, for example. Or publicly expose my web searches, associated with my phone number (which my friends or employers would recognize).

It's basically one less layer of indirection, which means much less plausible deniability. It's not a hard line but there's definitely a gradient they're moving down.