A big issue with fingerprint-only devices is water. If your finger, the reader or both are sufficiently wet, most readers just don't work. Most touchscreens also don't work too well in those conditions - certainly not well enough to enter a secure alphanumeric unlock code - but enough to pull up a map.

I've had my old iPhone 7+ turn into a charged brick multiple times in the rain. Never happened with the faceID phones.