I think the popularity of phone numbers is not because it’s a good auth factor but because it is a little more work to Sybil flood with generated identities, co

I think the popularity of phone numbers is not because it’s a good auth factor but because it is a little more work to Sybil flood with generated identities, compared to say email. So it’s not for our security exactly, but more for the company’s anti-abuse systems, and maybe the marketing department that loves hoarding phone numbers. That it works as a second factor is just a “happy” coincidence. Which in turn annoys me to no end given that phone numbers are regional. Having no access to banks when moving, let alone traveling, to an area with no cell service or a different country, is infuriating. It’s like “what’s your mother’s maiden name” all over again.