The real reason is that they want to save money on the text messages (outside of the US they need to pay $0.05 each time), not because they actually care about user security.

Like when xitter ran out of money and didn't pay their sms bills and people were locked out of their accounts

Sadly the article is very light on how this actually works. I'm guessing it involves setting up an authenticator on the phone (something they encourage anyway) and just using a QR code as a new way of interacting with it?

How am I supposed to scan a QR code sent to my phone… with my phone?

I'm confused about how this is supposed to act as a second authentication factor 🤔

Qrs don't seem safe to me
Scanning a Qr allows the installation of malware apps so I can look at a restaurant menu, & ding my card for recurring charges?