That’s a little disingenuous. They’re simply saying “I know my evidence is light but I haven’t seen any stronger envidence to support the counter argument”.

The “great resignation” will be more pronounced in different cities and professions. Eg I’ve noticed London based cloud engineers such as DevOps seem to be really affected at the moment whereas a lot of friends in other industries haven’t seen any change at all.

I think you misrepresent the comment, which was more "I know an anecdote cannot prove this, but..." Believing something while being aware your experience isn't really proof is not "faulty reasoning", since the awareness doesn't tell you your belief is wrong. It just alerts you that you should be open to additional evidence. (Which is always true, but we have to prioritize.)

When there is enough anecdotal evidence, that is consistent, you have to consider that the researcher is missing something. In this case, there might just be a misunderstanding - the economist is considering all jobs, whereas this evidence is coming from experienced tech jobs. The evidence is multi-faceted - people quitting, more hits from recruiters, etc.