My guess is that it’s the easiest and cheapest way to set up “MFA”.
TOTP is cheaper.
SMS is actually expensive at scale. An example would be Signal, the messenger app that doesn’t use SMS. They have overhead for sending backup codes/new account creation/Verification/etc… https://www.wired.com/story/signal-operating-costs/ 6 million a year. API integrations for SMS messages/codes are still like 1-5 cents per message.
TOTP’s requirements? A reasonably accurate clock on the server, and storing the shared secret in a database.
It takes several SSDs to make up the capacity difference between an HDD.
I run 62 16TB HDDs. To make up the same capacity in SSDs I need 2-4x the bays. I don’t know of any cheap systems that can hold ~250 bays of ssds.
So an SSD that may only take 1-3w all day… 2-4x that is already equal to the HDD regardless. You’re not going to make any ROI metric here.