The United States is the biggest music buying country in the World purchasing up to 35% of the Worlds music today, 75 % of Americas population is white, 12 % Black, 12 % Hispanic, 1 % other, for hip-hop artists to have reached the numbers in sales that they have achieved, simply couldn't be done, without white people buying their music, and they have been buying into hip-hop since the early to mid eighties, and not just since the jay-z's and ja rule's came around. Honestly white people have been a major buying power in black music since before hip-hop even.
It wasn't because they weren't buying Brand Nubian, or Tribe, that these artists couldn't hit gold, it was because they were busy buying other artists records, such as N.W.A., Ice Cube, Ice-T, Public Enemy, EPMD, Beastie Boys,... if you remember correctly what Native Tongue and Brand Nubian stood for, and were up against as far as competition.
Have you ever been to New York Mr. C? New York is a very diverse city, there are people from all walks of life, some neighborhoods are all black, some are hispanic (dominicans, puerto ricans,...), some are white, some jewish and some are a very colorful mix. I been going to hip-hop shows in New York since the mid nineties (1997), and the crowds there are very diverse as well, heads from all these different walks of life come out to support an artist. If I remember these Smif N' Wessun and Black Moon videos you speak of, there is a white cat that comes to mind, who was in most Black Moon videos as far as I remember, which was Dru Ha.
CM crew from NY is a good example of a crew in New York which was racially very diverse; blacks, hispanics, whites, and all of them get down! Then on the other hand you have a lot of crews who come from neighborhoods where there are no white people, such as East New York, Brownsville, Flatbush, LeFraq Queens and sorts. Biggie's neighborhood Do or Die Bed-Stuy is racially mixed for example, whites, blacks and hasidic jews.
New York is not a strong buying power in the music market either, it is simply the marketing capital, Radio City, the biggest music buying public in the U.S. is the Midwest, followed by the Southeast, and then the West Coast. In New York cats used to dub tapes, unless you were a DJ, the Ca**ette tape was the most popular format in NY (for Walkmen and such), this is where people like Raekwon were smart, understanding that he might not be able to sell his Cuban Linx album in the numbers he wanted, he made the ca**ette tape purple, which sold in NY! The first Cuban Linx album to this day in NY is not refered to as 'Only Built For Cuban Linx' but simply as 'The Purple Tape'. Raekwon even calls it this himself at his concerts.
If you check youtube for some footage from early rap concerts, I guarantee you will find white people in the crowd, why you think Def Jam first signing were white rappers? why you think Timex Social Club headlined their first Tour in '86? To get the spending power in America behind it!
I am not trying to defend a race here, I am simply trying to correct some statements that I simply find not to be true. And again Sage Francis has not had that big of an impact on hip-hop, I would say Atmosphere and Rhymesayers Entertainment come closest for what you talking about, but if you look at who handles their distribution (now with Warner Music Group), Navarre Corp. handles mostly Punk Rock labels, I know kids who love hip-hop and hardly know about Rhymesayers, and it's all gravy! I'm not a big fan either, but they simply offer an alternative, and I can appreciate that, but to say they filled a Gap is going a bit far don't you think?