"If folk music means "not having any known composer", then studio recordings of soul music aren't "folk music".

But if folk music means music that folk embrace because it comes from and expresses their very essence,then studio recordings of soul music are folk music."

Folk music doesn't actually 'mean' the first of those things and the second 'meaning' is so vague that it means anything you want it to mean - but, hey, why not just make it up as you go along!