As a scientist it makes me want to pick up a heavy object and cosh the AH every time I hear this phrase.
It's a meaningless put-down. When you need a new solution to a problem hypothesis are formed surround it that fall into a number of categories: 1. Wild-eyed unfounded speculation that merits no further consideration. 2. Reasonable hypotheses that have nevertheless been soundly disproven by incontestable evidence; 3. Hypotheses for which there is some evidence, though it is not firmly established and more evidence is needed. 4. Hypotheses that are soundly supported by overwhelming incontestable data.
Grad grinds - the guys who never had an original idea in their lives - dismiss category 3 as "anecdotal" every single blessed time. It's what they do. Sure it might not work, but of all the ideas that do work, this is where almost all of them come from.
Fauci might be a careful bureaucrat, but he is never going to figure out how to solve a new problem.
I wouldn't use the word "anecdotal" for this either. But the distinction he was drawing between the existing evidence and evidence from clinical trials was valid.