Regarding color, I think you're at least a decade late. Eminem released The Slim Shady LP in 1999. Then you got Beastie Boys, Aesop Rock, El-P, Atmosphere, etc.
Let's not forget 3rd Bass, Cypress Hill, House of Pain, etc. White rappers have been around forever; to act like they're some sort of new or even remotely rare phenomenon is kind of silly at this point.
I'm just pointing out what the perception might be which caused the author to pick that headline. Plus, really you can only pick a handful of successful white rappers, for the level of success we're talking about here. Black rappers are far and away the majority.