If the fake disease is in the medical textbooks, wouldn't doctors have diagnosed for it? For eg: Miasma theory and bloodletting were dominant, yet incorrect, me

If the fake disease is in the medical textbooks, wouldn't doctors have diagnosed for it? For eg: Miasma theory and bloodletting were dominant, yet incorrect, medical doctrines used for centuries until the late 1800s. Miasma proposed that foul-smelling air from rotting matter caused diseases like cholera, while bloodletting (phlebotomy) was used to balance bodily humors.