That’s not how it works or the physician was incompetent.

That's why Perdue was in so much trouble. They got doctors to write tons of oxy prescriptions, including doctors who were NOT pain doctors and thus didn't fully understand proper opioid treatment. So the person would go in for whatever minor thing, they'd walk out with a big oxy prescription, no ramp up or ramp down just take these for two months and then stop. And of course a lot of them got addicted.

The doctor has a valid moral claim not to promote deadly addictions.

Sure. And that's exactly what a responsible pain management doctor does. They see their patient on a monthly basis, it's not just a 'here's a self-renewing script have fun'. I think if you had more experience / visibility into responsible pain management practices you might have a different view.

They can, and the doctor is the most qualified person to make that assessment.

And that is my point exactly. I am NOT arguing that a patient should walk in and say 'omg doc i'm 10/10 it hurts so bad please give my oxycontin 25mg extended release 2 per day 6 month supply here I wrote it out can you sign this prescription?'
I'm NOT saying that a doctor should take a patient who they don't believe is in pain and blindly prescribe dangerous dosages of opioid pain relief.

I AM saying that a doctor SHOULD NOT say 'you broke your arm and have 47 stitches, you say you're in pain, but on my scan it looks like the arm is healing so too bad try not to think about it'.