I don’t wash it to kill or remove germs; I wash it to moisten it to hold the seasonings on. And i’d rather the seasoning layer not taste like old blood.
Old blood?
That probably gets to the original point to it—when people raised and killed and cleaned their own chickens and then took the cleaning steps that commercial distributors now do to assure no blood, feathers, etc., are left in an unsavory way.
Then such practices got passed down through the generations.