"I just checked. "Rapper's Delight" cracked the US top 40 in 1980, for chrissakes. That's the mainstream Billboard top 40, not one of the more specialized charts."
I was gonna say - and Queen's Annother One Bites the Dust (initially a non-single picked up by black radio stations) followed not too much later bringing rap or hip-hop into rock (though Aerosmith had been there earlier with their original Walk this Way from Toys in the Attic in 1975). Rhythmic music with rhythmic, but largely spoken lyrics has been with us now for more than 35 years at least, of course it has rubbed off on a lot of other styles.
And the rhythm guitar from Eminem's 8 Mile could pass as a backing track for a myriad dark and doomy heavy metal songs. I can just envisage Rob Halford, Geoff Tate, Ronnie Dio or Bruce Dickinson hollering over it.
All kinds of influences merge and that is generally a good thing.
As Herr Osterberg has already observed:
I just learned that Iggy is a leftie and can't tune a guitar. But I'm proud of myself: It's already May 8 here in Germany and I have inadvertently posted a clip that contains "it's what Hitler didn't like". What a way to celebrate!!!