Certainly the effectiveness of affirmative action is independent of a consensus around affirmative action's effectiveness.

Affirmative action is a widespread policy and has been for decades. Is its effectiveness now conditioned on consensus that the policy is effective? That is a ridiculous rhetorical trap: If anyone expresses mere skepticism that affirmative action has not been effective, then that person is by construction the cause of its failure; conversely, if everyone does agree that affirmative action is effective, yet disparities have persisted (by just about any measure), then everyone is lying to themselves and one another in order to achieve a political consensus that perpetuates the struggles of black Americans (note a parallel to the rhetoric from supporters of Jim Crow, "the peculiar institution" and various progressive "scientific racism" programs like eugenics). I'd consider the latter scenario downright evil.