I have the same when logging in to my Google account provided by my employer. I don't have 2FA set up, so they have no prior knowledge of my phone number. I'd also like to understand how this is possibly useful? In my case I was travelling, so had no option but to enter the number of the nearest available random person willing to lend me a phone for the purpose, with no idea what it would be used for. It is cynical t…
What you're describing is a "cost proof" - namely that the user has something we can verify that costs some amount of money and is unique. So when the service I work on asks for a phone number verification, it's not always to determine your ID - it's to cut down on spam from users unwilling/unable to set up tens or hundreds of phone numbers, which I imagine is the majority of spammers. Adding it to existing accounts,…
They're doing it on Chromebooks because you're using Google's services. A Chromebook is just a Google Cloud Computer; users aren't expected to use one without using Google's services too.