Macklemore is one of only four new rappers to have gone platinum in recent times. He's indisputably one of the genre's most successful superstars. And his roots are only tangentially in hip-hop. As has been pointed out many times, his success took place with a very white grassroots audience.
His delivery has been, in the past, compared to rappers like Slug from Atmosphere and Sage Francis. Even if you think the comparisons are overstated, though, aesthetically and philosophically, his heavily moral approach and independent, grassroots grind owes a lot to the indie hip-hop scene of the late 1990s—and that's a scene of which Rhymesayers played a significant role. As Jon Caramanica put it in a recent piece for the New York Times, it's "message music": "These are the values and themes of the old hip-hop underground, independent rap’s late-1990s-to-early-2000s heyday, the womb for Macklemore’s style."
Of course, Rhymesayers was a more complicated, idiosyncratic music than their successful aesthetic offspring would suggest. Macklemore has never, to our knowledge, released a song that ended with him murdering cattle. Nonetheless, it's tough to imagine the sound of today without the impact of late-90s indie rap: from Scribble Jam to the Hip Hip Infinity website to the Rhymesayers record label.