Why don't more rappers draft one producer to take care of the beats for an entire album? Some of the greatest hip-hop albums in the history of the genre sound that way because they have such a cohesive sound, with themes that can be revisited and sonic markers that can work with the lyrics, not just next to them. Think about the greatness of Run-DMC (whose Jam Master Jay handled all the beats), Public Enemy (with the Bomb Squad matching Chuck D's aggression note-for-note) or the insular worlds created by the early work of the Neptunes (like Clipse's Lord Willin') or Timbaland (like Missy "Misdemeanor" Elliott's debut Supa Dupa Fly). For the best proof that it's a system that works, look no further than legendary tag team Gang Starr, whose critically-acclaimed smash album Hard to Earn was released on this day in 1994.
Gang Starr consisted of rapper Guru and producer DJ Premier. The premise was simple: Premier crafted the beats (cobbled together from soul samples and his deft scratching) and Guru provided vivid, literate lyrics delivered with a deadpan flow. They were never hit makers, but every album in their catalog is considered something of a modern classic.
And they never sounded right apart, either. Though Premier lent out his production services to dozens of other rappers (he produced everybody from Snoop Dogg to Alicia Keys to Christina Aguilera), nobody ever seemed to wrap around the tracks the way Guru did. And Guru experimented with various versions of his Jazzmatazz series, but he never sounded as sharp as he did next to Premier. They were a formidable duo who casually tossed off jaw-dropping tracks like "Mass Appeal" (Hard to Earn's centerpiece track) like it was easy.