Mark Slaughter of the famous hair metal band Slaughter came out and said that there is a widespread misconception that grunge killed hair metal. He claims MTV hired a new president who was also a program manager at KROQ in California and he came out and said he wasn't going to play hair metal any more - and it was his decision not to play that music any more that killed that entire genre.
He readily admits there was an undercurrent brewing with people getting tired of the hair metal scene and labels essentially trying to create the next big thing, all in the image of these successful bands, but its interesting to note how one guy basically cratered the entire genre in the span of less than a year.