I finally set up 2FA on my Google account this weekend.
It struck me as incredibly odd that Google requires a phone number to enable 2FA. NIST recently advocated against using SMS for OoB auth. [0]
If I had been an account hijacker with the password (e.g. obtained via phishing) it would have been ludicrously simple for me to enable 2FA on someone else's account.
I don't understand, I already have an Android phone with Google Play Services installed. Why isn't pressing "Okay" on my phone sufficient? It's certainly not any more insecure than an SMS.
What I view as even worse is on the first attempt the SMS didn't go through, so I asked Google to give me a call. Evidently my provider blocks whatever number they're using to call out of, so my phone never rang. But Google left the verification code anyway, AS A VOICEMAIL!
My inner tin foil hat says Google wants a phone number for other purposes.
[0] www.securityweek.com/nist-denounces-sms-2fa-what-are-alternatives