All the joking aside, there is actually a serious flaw with this methdology, which is generally the problem with and scientific studies with A vs B comparisons and there is a much more rigorous approach used in the more physics based sciences (including chemistry, electronics, other forms of engineering, and in biochemistry).
The FDA approach is actually medieval.
The approach used by modern technically sophisticated organizations is to develop an understanding of the controlling mechanisms, demonstrate and ability to operate those mechanisms and then demonstrate that when the mechanism is controlled or operated the desired effect is obtained.
We don't deliberately test planes with inverted airfoil shapes or inoperable control surfaces and compare with properly operating things.
“We don’t compare...”
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I understand your point, but you may have forgotten something that is all too common in the literature, that the “mechanism of effectiveness is not completely understood” in so many medications. I was just reading earlier today on how the mechanism by which Tylenol controls fever is no better understood than the mechanism by which it controls pain. There are some fascinating theories on how it works.
I have read alternate theories on the antiviral action of chloroquines on sars type viruses. My preferred theory, the more I read sounds less and less plausible to me.
One fact that supports your point is that right now we got nuthin else and the standard anti-virals are disappointing especially according to the standard by which Plaquenil is seen as effective.