Oh please.
Think of the great white rappers which never even get a mention... people like fucking Rugged Man who demonstrate insane levels of skill Universe's beyond 99% of all black mainstream rappers and then Wayne gets called the best rapper alive

, or the likes of Asher Roth who despite what you may think of him: CAN spit very well and IS really thinking hard about what he's doing and why, who get shit on just BECAUSE they're white...
And all of the absolutely mind-numbingly retarded black rappers who get a pass just BECAUSE they're black...
It swings both ways and at the end of it - it's just about making catchy songs. Do you make memorable songs which resonate on a world level or do you just spit dopely... Kendrick made an acclaimed album, but did his singles and style resonate on a world stage like Macklemore's did in 013? Nope, not even close.
It's not a fucking race thing, it's a popularity thing. It's a catchy thing. Rosenberg: shut up you cock.