That is fine, but that ain't the same thing as it works. Doctors are very much allowed to prescribe placebos. Here WebMD says 50% do exactly that:
WebMD provides an overview of treatments for chronic pain, from surgery to herbal remedies.
www.webmd.com
This randomized clinical trial examines whether hydroxychloroquine or lopinavir-ritonavir is effective for reducing hospitalization among high-risk outpatients with early symptomatic COVID-19.
jamanetwork.com
This is the same debate, 90 doctors say X does not work, conservatives are drawn like a moth to the flame to the 10. The 10 MUST be right. Even if they prescribe simply for a placebo.
Here is one study where they combined the results of 28 trials. From the opening:
We found that treatment with hydroxychloroquine is associated with increased mortality in COVID-19 patients, and there is no benefit of chloroquine.
Hydroxychloroquine and chloroquine have been investigated as a potential treatment for Covid-19 in several clinical trials. Here the authors report a meta-analysis of published and unpublished trials, and show that treatment with hydroxychloroquine for patients with Covid-19 was associated with...
www.nature.com
Trials are ongoing with ivermectin. Maybe they find something. I have never criticized doctors who prescribe either (but I have people who buy such drugs on the black market and self medicate). A doctor has the right to prescribe even if it only is to help a patient's psyche. But even that comes with a risk. If said patient than takes more risks because they are taking a placebo, they are in greater danger.
And there lies the big problem both with placebos and most masks. It is the car problem, the safer we make cars the more dangerous people drive.