Proof? You have hardly provided anecdotal evidence. Why is the burden of proof on me? You're the one making a claim. I'm not saying hip-hop promotes anything. I'm just stating the fact that Hip-hop is a collection of art forms that comprise a culture. Dj-ing, Breakdancing, beatboxing, beat-making, graffitti art, and rapping; these are capable of promoting neither maturity nor immaturity, nor anything else for that matter.

How does an art form make the people who consume it do anything? Does viewing a Goya painting make people go eat their children? Does listening to a Wagner opera turn somebody into a racist? If your claim about a type of music ( in this case Rap which you are broadly painting as "hip-hop") causing immaturity was sound, then by the same accord of your reasoning, heavy metal fans everywhere , after 40+ years of hearing lyrics about devil worship and violence, would be killing people in massive numbers and practicing black magic when in reality they are not, and jazz fans everywhere would be addicted to heroin like their heros Charlie Parker, Billie Holiday and many others.