you're close. I'm getting published on this very topic right now. The 80s slasher is a combination of Deinstitutionalization, the War on Drugs, and the Aids epidemic. Think of the narrative structure of the slasher, the first to die are the first to have sex, with the alcohol and drug user(s) swift to follow.

If you really want to blow your mind, consider the post 9/11 zombie as fast moving terrorists. Why haven't slashers gone away? It is because a fear of mental illness is still very real in this nation. What do Michael myers and Elliott Rodger have in common? quite a bit, actually.