Sms hijacking doesn't "convert" anything anymore than someone with a telephoto lens "converts" an old-style hardware token to a password. (Yes, I know the p in otp is password, and called that because it's entered by the user. It's not a password in terms of a factor you "know" because it's time-limited.)
These are also fluid ideas that are used to describe roughly different failure modes for different types of authentication:
Passwords are thought of as things the user can disclose.
Totp and other "second factors" are thought of as things that must be stolen, or if disclosed have a very short viability time.
Biometric are things that can't be disclosed, but can be lost, and (and when properly implemented) not stolen.
You're trying to argue that these categories of authentication factors have hard lines and definitions when they're fluid categories being used to think about failure modes of a method. Each specific authentication method has its own strengths and weaknesses.
Also, sms hijacks require a lot more than simply "knowing" a phone number. While sim cloning and ss7 attacks are known and very possible, they're still fairly complex. You can also social engineering tech support at phone companies to activate your sim for an account, but that is also significantly more difficult than simply "knowing" a phone number and also a failure of the authentication the phone carrier is using.
