Google tells us:
The diagnosis is an important tool for you and your doctor. Doctors and therapists use a diagnosis to advise you on treatment options and future health risks. Another reason a diagnosis matters is that it tells health insurance companies that you have a condition requiring medical care.
A diagnosis is not a tool. It is an opinion used to justify a professional response, not infrequently by another provider. So, it is a strategy employed by medical and surgical personnel to promote enterprise that they expect someone else to pay for.
Will it help the patient? That is not the point. “Future health risks” moves the enterprise into the unknown. Oddly, and this probably a philosophical issue, dealing with the unknown allows for greater certainty.
That explains why the cardiologist, more than two years ago, was able to sound so certain about the recommended surgery whose rejection then prompted prescriptions for a few pills, almost all of which I have since discontinued. The risk level is low for a solution to a potential problem.
On the other hand, if the potential is given priority over the actual, then the actual may end up being ignored.