Switching to authenticator for 2FA, why does Microsoft account force you to keep using SMS?

I am trying out open source authenticators for 2FA and got one setup on my Microsoft account.

I no longer want to use SMS or email, because if they get compromised, what is the point of using the stronger TOTP?

I went to remove SMS and Email as verification methods on my Microsoft account, but when I went to remove SMS, it wants another phone number to keep SMS as a method... am I missing something here?

Isn't the point …

2fa account authenticator authenticators compromised email microsoft open source point privacy remove setup sms stronger totp using what is