Nothing you just wrote about would be resolved if we were to let patients die from lack of treatment. Hell, none of what you wrote about is even comparable, for exactly the reasons I've already explained.
I really don't understand why you're having this difficulty: If giving no treatment carries a known high risk of harm to the patient, then no treatment is not an ethical option.
I'm not dismissing the efficacy and usefulness of placebo-controlled trials. I'm saying it's unethical to not treat patients with fatal illnesses if a proven treatment exists.