In Android 6.0.1, there is an option to 'Enable fingerprint' in Application lock, but it forces the phone to be unlocked via fingerprints.
Since most likely, the application lock only prevents sensitive data (messages, account information, etc.) from being accessed/viewed easily, it makes more sense to me to selectively allow usage of fingerprint to unlock apps (and not the phone) because for the phone, a secure PIN/Password makes more sense.
Why is it so? Is there a way to achieve the desired result (using no third party tools)?