That's not a rule of thumb. That's what idiots use as a measuring stick when they can't bother to do any research themselves.

Common Self-Ascribed HN Logician: "Wow, the Wuhan lab leak sounds CrAzY!! CNN is telling me it's a whacko conspiracy theory by our CrAZy SeNsAtIoNaL PrEsIdEnT! Checkmate, Mister Frump!! Crazy things don't happen! RuLeS of ThUmB!!"