I absolutely refuse to give a numerical answer unless they first give me an objective calibration for the numbers. I recently got into a minor argument with a nurse before a minor surgery. "If you won't tell me a number, how will I know if I need to give you a painkiller?" "If I'm in enough pain to need a painkiller, I will tell you."

The number scale attempts to turn a subjective interpretation into an "objective" value. Instead of having to actually listen to people and apply training and experience to judge which treatments are needed, the number system de facto pushes that decision onto the patient so the doctor/nurse/etc only needs to follow a simple set of treatment rules. Similar to black box "AI" used in e.g. criminal sentencing and employee evaluations, the numeric pain scale is yet another example of a fundamentally subjective situation being laundered into a supposedly "objective" value.