If I understand you, your theory is that unless Congress and the Presidency are both under the complete control of the Democrats, they're powerless?

By that theory, the Republicans from 1994 to 2001 were powerless, since they didn't have the presidency. Clinton had no power since the Congress was Republican through most of his terms, Reagan could do nothing since the Congress was Democratic, and the Democratic congresses of the previous 40 years were powerless because presidents were mostly Republican.

Well, we actually did have the Carter administration, where Democrats pretty much ran everything. I wasn't impressed.

And if they did have all the power, what would they actually DO with it? Pander? The Catch-22 is that if Democrats actually DID create policies that brought more black people into the upper classes, with higher incomes, better educations, and independence, when it comes down to it, what the heck would they need Democrats for any more?

No, as long as it remains all about promises, the black people will stay put, stay dependent, and turn out reliably at the polls.