Is there any data on what kind of hits to enrollment were taken by facebook, gmail etc when they added requirements like a phone #? Maybe it's buried in their sec filings. Anyway, this "cat and mouse" game is probably irrelevant. They're not looking for and don't need a perfect system. Bc 99% of the public couldn't care less about handing over their information.

Google does not require a phone number. They may ask for one and tell you it's for your own good, but you can skip the request.