Man, Rap(and the music business in general) be bullshitting. You can have someone(who shall remain nameless) who can't rap worth shit, have a #1 rap album while Chino XL, who i and a lot of other people think is one of the greatest rappers/lyricists of the past 20 years(hell, ever), might do only 40 or 50 thousand units tops(minus his first album). I am aware that there's a bunch of reasons why that is so, but it sucks when half-assed is rewarded, but skill is not.
Anyway, so my take on why Chino XL doesn't sell a shit load of units is because his raps go over a lot of peoples heads. With a lot of Chino's raps, a person has to really pay attention to what he's saying. He's the type of rapper who's music(lyrics) has to be listened to a few times to fully get what he's saying.... That and some of his beats aren't super catchy... So, dude raps in all kinds of crazy ass metaphors and such. And he has a genius level IQ to boot(Mensa member).
One last thing. A few people think that Chino copied Eminem's style, but that's not accurate. Chino's major label debut came out in 1996(on American Records), and Eminem's major label debut came out in 1999. Eminem's first album did come out in 1996 as well, but Chino's first single(with Art Of Origin) came out in 1992, so...