I disagree, in the first place, he is conducting his survey in western world where the climate is mild, cold and snowy. He should survey as well in Middle Eastern and Sahara subcontinent were hot and humid conditions occurred during summer time. Even animals need a bath everyday.... as we do human needs too!!!. what about those people eating spicy foods as well as onions, garlic, if they are not taking shower everyday, imagine how the smell it stinks?.
I believe that taking hot shower it caused baldness and also hereditary. Using often shampoo with high contain of chemical it cause baldness as well.
Use coconut pressed milk, it's natural and looks your hair shiny without any chemical content.