It's only a myth if it's disproven. All four of my churchwardens smoke cool and soft with no bite. Besides, I find myths are often laced with a grain of truth more meaningful than the truth framed by common consent.
It has been disproven... Repeatedly. Scalding your tongue is when you burn it through heat. Tongue bite is a chemical burn. Myths laced with a grain of truth can also be the most dangerous, like the myth of choking on your tongue while having an epileptic seizure leading archaic practices of trying to insert spoons and other objects into a victims mouth, resulting in making the situation worse through broken teeth, bit fingers and chocking on foreign objects.