The private key method is not the recommended one [...] is optional [...]
It simply should be removed! I see no reason to keep it when safer alternatives exist.
Any app asking for a private key is a NO-GO for me!
I have never integrated this option in any of my applications and nobody complains about it.
As a witness, security should be one of your main concerns. Educating users about it too.
The option will be removed.
Glad to hear it. Thank you for considering my feedback.