Insofar as vocal technique has been influenced by the use of microphones and other electronic gear, contemporary folk music has been influenced as much as ANY genre.

Use of mikes allows the singer to adopt a style and persona that more-or-less replicates the way a person would sing in a very intimate setting ~ a small, quiet room. And even for those of us who never perform professionally, or at least not to large crowds, everything we ever listen to has been influenced by these factors, and thus we are all under the same influence.

Just as film acting is more "natural" and subtle than old-fashioned stage acting, so is singing/"crooning" in a world of amplification more personal and low-key ~ or, at least, potentially so ~ than performing to a loud crowd in the days before mics and speakers, etc.