AAVE is a distinct dialect with its own grammatical structure. Kanye is very much literate.
Besides, the usage in that verse is intended to highlight the disparity between the type of formalistic language use taught in school and how the average person on the street speaks. "Some people graduate, but be still stupid" is a particularly obvious example of this.
... I have spent a significant amount of time psychoanalysing Kanye's music. He's basically challenging the listener to do this on later albums, particularly Yeezus and My Beautiful, Dark, Twisted Fantasy.
Something is very wrong with the italic function on this forum.
Methinks ye are missing the point. Maybe you are thinking in lines that are too straight (my terminology).
I wouldn't know his music from any others of the genre(s) as it ain't my thang. The closest thing to rap I can stand is the Addams Family Rap from back in the day. There is just no appeal to me at all within that style. But words have meaning.
My take on what you posted was Kanye dissing on education, making those who have been educated lose their "streetness" to use his terminology. Which is very sad to me. I have met many people who are actually very smart and quick witted but who are ignorant and illiterate, and yet they think they are "all that" because they be from the hood, yada yada yada. What they don't realize is that they sound stupid when they talk, look thuggish in how they dress, and cause concern in others with how they act. Most are just working on being walking targets for the urban shooting range.