Rap is a vocal art. It wasn't called rap centuries ago in tribes in Africa, it was a way to address issues among the tribe. In the jazz age, there was a vocal style called Scat. Sarah Vaughn, Louis Prima, John Hendricks, The Manhattan Transfer and others do it.
The Mummers, a group of theatrical performers, would have parades in Pennsylvania. The performers would dress in lavish costumes and accompanied but musicians of percussion, woodwinds, string(guitars, bass and banjos and accordions). Each group would perform a grievance in music in the form of themes like pollution or violence. It was a practice that was done in ancient Rome. The Mummers still perform in Pennsylvania to this day.
Artists these days are not even to be taken seriously in this respect. Amy Winehouse didn't like her first album Frank after it was out. She was merely trying to top herself. Not listening to her fans as to what they thought. Digga may be just talking.