If it has nothing to do with minorities, then why don't we hear, hispanics, caucasians, asians, etc using ebonics? An underclass? No such thing. You want to get ahead? Study and work.
Broken educational system? I'll only give you part of that. You can still learn how to speak English in school, you just have to want to.
Just because what passes for enlish amongst the uneducated or under educated rednecks or hispanics (spanglish) hasn't been given "recognition" like Ebonics, doesn't mean it doesn't exist.