According to the closed question statistics the most used custom close reason with 12 occurrences in the last 90 days was:
I'm voting to close this question as off-topic because it's based on false premise.
I personally find this sentiment worrying and counterproductive, as I wrote earlier:
Just because a question is based on a wrong premise, it does not mean it is not worth asking. The wrong premise must come from somewhere. I truly believe that debunking a myth, [...] is far superior to closing it down, preventing it from getting more attention.
M.A.R. pointed out that just because a question is closed, it doesn't prevent it from getting more attention. That is correct. However, it does prevent it from getting a useful answer that would debunk a (/an obviously) wrong claim.
I would like to understand why this is so popular. It is not only one person to suggest this line of reasoning, but there are others who agreed to close a question based on this.
Of all possible reasons to reject a question I think prior knowledge shouldn't be among them; I'd encourage anyone to take the opportunity to educate as a well crafted answer can lead generations to come down the right path.
Disclaimer: Please note that I am not saying that all of the questions that have been closed with this reason are a good fit for the site, I am just saying that the reason to close them is terrible.