Online banking is broadly less convenient than the banking app on my phone. With online banking I need to login with my creds every time, with my phone it is secured with FaceID, so I basically just open the app and I'm good to go. This is secure because Apple prevents unsigned FaceID cameras from being used with the Secure Enclave, so an attacker can't just steal my phone, swap the FaceID for a component that always says "yes" to auth requests, and steal all my shit.

This is doubly a concern because phones are broadly much more easy to steal/lose than your computer. Additionally enabling FDE on my computer is not a big deal, but doing a full decrypt of my phone every time I wanted to open it would be onerous.

Mobile phones are just fundamentally different devices from desktops. I want my desktop to be open (and secure, but lean towards open). I want my phone to be secure and functional.