i'm no authority on this, but imagine you are talking about any other type of music.
k-pop, country, metal, grunge, classical.
what do you think of these genres, and more importantly the people who made them?
if you go into country music thinking, "southern americans are really backwards and out of touch," then you would use their lyrics as justification. or grunge thinking they're all moody drug-abusers, obviously, metallica's "master of puppets" would reinforce your preconceived notions.
rap- like every other genre- is a wiiiiide genre of music and many people create it. people of different genders, political orientation, sexual orientation, upbringing, etc make it.
rap isn't just talking about one thing. it is a very diverse genre that expresses many issues, and yes, some do intentionally depict stereotypes and reinforce them, but a large amount simply document's the artist's feelings about their life. like any other genre.
the point is, anything can "reinforce stereotypes" if you make it so.