I was thinking that, when I tried to enable 2FA on Twitch. Allegedly, they support TOTP. But only after verifying your phone number. And they even check that it’s a mobile number (I tried using a VoIP number that can receive SMS).

My phone number is probably the least valuable thing Amazon knows about me, I figure.

Phone numbers are basically super cookie identifiers unless you make a new phone number for each account and use different aliases & maybe addresses for them too. They all sell into centralized information systems and create profiles about you that are very detailed, which includes banking, income and credit info. So yes, the phone number is incredibly valuable, especially a place like amazon that shows different prices to different users and who's recommendation engine drives a lot of sales.

Phone 2 factor is pretty much the only kind of 2 factor most people will accept, and for most people the phone number probably has better security than most people's emails, because most people reuse passwords, while with phones you had to do a special non-password effort for them.

I’ve always figured this was what they wanted. They probably tie it to your IMEI so they can track you everywhere online and in the real world.

E: Seriously? This is a multi billion dollar industry. Oh no, Google would never do that…