The "Satanic Panics" of the 1960's and 80's didn't actually originate with the JW's themselves
The 1960's belief that unclean spirits could be brought into your home via inanimate objects seems to have been triggered by a 1957 book by a French Monsignor on the dangers of the spirit world. The idea spread across denominational lines and even into pop culture via movies like Rosemary's Baby. The JW's were more enthusiastic in spreading these "Demon stories" than most, but they were hardly alone.
The hysteria of the 1980's was very similar, only in this case the trigger was a book by a Canadian psychiatrist entitled, Michelle Remembers. This book told the story of a woman's childhood abuse at the hands of a satanic cult using the discredited practice of recovered-memory therapy. As a consequence, the idea that an organized conspiracy of satanists were targeting children via cartoons like The Smurfs also crossed denominational lines and found fertile soil among the JW's.