I mean an easy answer would be to say it's the same reason why Rapsody has a big online following but not a big mainstream following. Sadly, people are shallow, and they want their female emcees to have that sex appeal. I think it's the same reason why people just don't care about female athletics as much, like the WNBA. Rah Digga is dope, Rapsody is dope, Jean Grae is dope, and they all do everything that great rappers do. Jean Grae has a really good and personal song about abortion, and she puts her life out there like a lot of the greats do.
I can't help but think the main reason is just because she's a woman, as fukked up as it is. Rapsody has said a bunch that she wants to be an all-time great emcee, not an all-time great female emcee. I mean it's definitely not because of the music. jean Grae made an album with 9th Wonder called Jeanius that's pretty much praised across the board. It's gotta be another reason.
Speaking of Jean and Rapsody, here's a nice joint that they both did over some Khrysis production