Londinia must be one of the younger grannies. Hairdryers have only been around for a comparatively short time. Previously the normal way to dry hair was to rub it well with a towel and brush or comb it into a style while still damp, or else to let it dry first then brush out the tangles. If you were among the many with hair as straight as pumpwater (you should have eaten your crusts!), your mother sometimes wound it up onto strips of cotton fabric and left it all night to dry into waves or ringlets, but that was for special occasions.
It is in fact better for the hair to dry naturally. Hot air dries out the natural oils, which then have to be replaced with conditioner.