> modern 2FA systems don't Sure, if you're defining 'modern' as something other than what's actually used by the vast majority 2FA users. Even for people who u

> modern 2FA systems don't Sure, if you're defining 'modern' as something other than what's actually used by the vast majority 2FA users. Even for people who use U2F or TOTP as their primary Gmail 2FA, what percentage do you think have actually correctly deleted their phone numbers from both their primary account and any recovery accounts? I have no idea, but I'm guessing less than 1%.