Insurance companies are huge FOR-PROFIT companies. Their goal is to make money for their share holders.
Patients' good health and quality of life do not add to the profits of the shareholders.
A person's insurance plan will pay the amount it decides only for the interventions it allows only for the diagnosis code it demands.
It is the patient who knows the condition that he or she wants to treat.
It is the doctor who knows what interventions can affect that condition.
It is the patient who knows the value of treating their condition. ("Value" means how much the patient is willing to do and pay.)
The doctor knows the cost of the different treatments -- both in dollars and in effort.