Somtimes you will find instrumentals on hip-hop/rap albums, I believe made to have no vocals to em.., I know it was a soundtrack, but Stanley Clark's instrumental from "Boys In The Hood" was one of the sickest instrumentations I've ever heard, well, back in the day it was.. Not a fan of it, but techno gets away with it.. I agree with dude, making a beat for Hip-Hop intended for no vocals is a different approach, and if done right, a very artistic on at that!
PM