<< But even Rock n Roll required being able to write lyrics, compose music, sing and/or play an instrument. What a concept! >>
Ok, Hip Hop requires the collaboration of 2 or more people, and the co-operation and vibe have to be so tight that the lyrics and the beat come together. Between the Producer and the actual Artist - there's multitudes of skills to be shown. Intuitive lyrics have to be written (not always the case ie. Cash Money). You mentioned "composing music", well, that's what a Producer does, which includes being able to play an instrument (the keyboard specifically). And as far as "singing" in rock goes, it's nonexistant. And guy over 30 can mumble into a microphone and sound as good as any Rock band.