Once a name has widespread use, humans are innately conservative and keep using that name, even when the reasons for assigning that name no longer apply. Take the native Americans, who for several centuries were called "Indians", despite fairly strong evidence even within Columbus' lifetime that the American islands were not just off the coast of India. Or the building in Amsterdam that is still called the "Nieuwe Kerk" (new church), even though it was built in the early 1400s and is no longer used as a church, so neither of those words in its name are literally correct any more.