Brakes are about stopping the bike. If/When you lock up the wheel, all your stopping ability comes down to a matter of how much of your tire is in contact with the ground. The one or two square inches (if that much) of tire rubber don’t care what made the wheel/tire stop rotating. So, if your “whatever” brakes are properly adjusted, and can lock up the wheel, how is one system better than the other? That being said, I will agree that there are certain conditions where disc brakes would be more functional than rim brakes…like descending mountains in the rain, for example. But otherwise, stopping is stopping.
Dan