dear, shimrod,
the crux of the matter is this, traditional singers such as Harry Cox, sang naturally, singing naturally,involves singing while breathing through both mouth and nose., because they are unaware that they are not singing in a particular way, they are just singing
trained singers are taught to breathe through the mouth whilst singing.
revival singers that you are so keen to criticise are following in the tradition of singers such as harry cox, and singing naturally, in other words they are singing without thinking whether they are breathing through one specific orifice, be it mouth or nose or any other hole.