That's a good point that it is more nuanced. The issue I think is that organized crime and unscrupulous governments are getting better at connecting these things so they are not as cleanly separated as they have been in the past. Just look at China. Essentially spyware and viruses are installed at checkpoints on people's phones and biometric tracking is becoming very commonplace. I don't think it will be long before organized crime begins to get better at this too. As such, being able to change that "something you know" is a very powerful countermeasure.
1. Something you have (e.g. your phone, in this case the Secure Enclave that stores the private key).
2. Something you 'know', e.g. your fingerprint.
Just having the fingerprint itself is not sufficient.