Frequenter Mendax
From Latin Frequenter meaning "often/in-great-numbers" and Mendax meaning "false/deceptive". The phrase is used to describe things that have been proven wrong so many times that they are no longer worth debating or considering scientifically.
Person 1: "Why don't scientists fight more flat earthers?"
Person 2: "Because the flat earth theory is frequenter mendax; its not worth disproving what has been disproved over and over again."
Person 2: "Because the flat earth theory is frequenter mendax; its not worth disproving what has been disproved over and over again."