You know that it's used for unlocking the phone, right? It's nothing like the use case you're describing.

You have to get a phone with one and use it for a week or so until its use becomes routine to really understand how big of a game changer it is. I subconsciously unlock my phone now every time I pick it up. It's amazing. Every day it saves me probably 60 seconds in total typing in stupid PINs, and those savings add up real quickly.