Biometrics are usernames not passwords. Biometrics should never be used on the sole authentication method they should only be used in conjunction with something else.
That such a meaningless slogan. Passwords and biometrics have different pros and cons, but they are the same in that they increase security.
Biometrics should never be used on the sole authentication method
* Biometrics is always better than no security.
* Biometrics done well is certainly better than a 4-digit PIN.
* Biometrics on an iDevice is in fact always used with something else, which is device itself: Touch/FaceID on an iPhone can only be used to access that particular iPhone. Ie. if you manage to steal my fingerprint, you can only use it to access the devices that I have set up to use my fingerprint. This means that my fingerprint alone is not of any value, unless you can also gain physical access to my phone. Compare this with a password which, if stolen, allows attackers on the other side of the globe to access to my accounts.