Google will automatically enroll users in two-factor authentication soon
Google hates passwords, so it's trying to replace them with two-factor authentication.
I originally moved to Google from Yahoo because they had the two part authentification - password plus messaged authentification number. Since then it has changed to simply recognising me through my device's signatures & the password set by me. It's always a hassle when I resurrect a device not used for months. I get request emails to my back up accounts asking if it is me.
What happens if someone loses their phone, or gets their number ported away maliciously (SIM card hack) ?
Carry a little black book.