Rap-based styles are just verses over a machine rhythm. A rhythm alone can't be called music. A 100-Ton press produces a perfect rhythm, and certainly it's not music! Early Blues players based their songs on the rhythm of the trains, adding melodies to that. Many decades later, Black Sabbath & Judas Priest members who worked in the British steel industry added melodies over their machine's noises and created what has become known as Heavy Metal. In short: Music = Rhythm + Melody.