I don't have the facts, but I want to suspect it has a lot to do with what I will call cultural connotation, of being a negro musician in his era. I see a lot of semblance to Nina Simone, and Lauryn Hill, and even Brown. Again, I don't have the technical know-how to break this down to "make sense". I am just making an assertion from the feels I get from this listening to these artistes, as a non-expert lover of music. I hope that makes any sense.