I would agree that autotune might have kinda change music (although when used in a deliberately exaggerated way it doesn't sound much different from a vocoder), but to me Cher's song is just one of the pop hits that helped popularize the effect. IMO, it's just a very well-produced pop song, which contributed to the rise of a form of vocal processing that's very widespread today, which is already quite a lot. But it's not revolutionary in itself, it's very much in keeping with all the codes of pop music. For the records, I'm actually a teacher in audio engineering at a college and Univ so I've been quite interested in the over-popularity of this type of audio processing in recent decades.