Honestly this is probably for the average user… Because Google doesn’t want to receive calls that XYZ (that uses Bluetooth) is broken from those that are tech illiterate in the general public and accidentally turned Bluetooth off.
My grandpa as an example would also not read your pop-up.
The general public is not concerned with disabling Bluetooth for more than a power saving or troubleshooting step… And even then, it’s going to be an accident more than a choice for a lot of people.