Modern day elite Democrats and at the top of their party are modern day plantation owners. They need to the blacks to stay where they are for the votes.
Let me explain. It would do Democrats no good for blacks to do better, to make more money, gain more wealth, become better educated, etc. It is no different than what they did with rural whites in Appalachia. Democrats needs a misery index. They need a problem of which many times they help create. Why? Here is the problem(which they may have created) and we are the solution. It is a cycle that never ends.
If suddenly Blacks were as affluent as whites(in not just money by other things such as status, home ownership, etc.) then, where would they turn for a voter base? They would lose it.
Just listen to Dems and follow their polocies. There is no way out. No real hope or light at the end of the tunnel. No path to escape. This is just simply true. Demoocrats don't want you out of your situation.