I disagree...
The subject matter is not as relevant, as the perspective a rapper uses to address a particular subject matter...
I am a middle class dude who has never seen a gun or cocaine...But watching movies and listening to hip hop, I sometimes get that dreamy infatuation and fantasize of selling kilos and winning gun fights against my enemies...Just like Nas was doing on "New York Sate Of Mind"...
So if I was a good lyricist with a good delivery, I could rap about all the social conscious staff, but also mesh in coke dealer fantasies, and the audience would accept it, depending on the way I present it...
And to me that's what makes a good rapper...
Good rappers like Pac, Nas, Biggie, Bone Thugs and many more, could go from dealing drugs, killing people for no reason, denouncing the system, respecting women to misogyny and etc all in one album, and still make the album sound cohesive and complete...
That's the test of a true lyricist...
In my, great artists (in any genre) are controversial, because life is not black and white...
Even a backpacker may feel like killing one day or consider selling crack when put in a tough position, if you have the talent to present your perspective in a convincing manner, and you have right music, you will be accepted...