About Alice Cooper, I don't know Poison, just that it's a later song. His music went to hell when he ditched the original band and hired professional musicians but he has an early greatest hits album, songs up to about 1974, that stands up to this day. They were one of the biggest bands in the world for a brief time and I think that counts for something too, because they didn't tone it down to be accepted. After that original band was no more he became a sort of washed up comedian who did ballads for and about housewives. Still, the original band was still one of the greatest glam rock acts because they had some great songs and they were very famous. The fame isn't important for itself, but because, like the Sex Pistols they awakened Middle America to this sort of underground music, put a sweet coating on it, and had lots of little kids listening to songs that were pretty rebellious and strange for the time.
I also don't see much difference musically between songs like I'm Eighteen and lots of the early 90's music led by Nirvana. They were very influential in many ways.