The people who I see arguing this most loudly (like Dinesh D'Souza) are frauds. There's no better way to put it. They aren't arguing in good faith about the interpretation of a "switch" (which you could do, because like all things, history and historical ideology is complicated), they're just spouting misinformation that I'm fairly sure they know is misinformation, for the purpose of muddying the political waters and selling books. The motivation is obvious: they want to claim that the Republican record on African-Americans is better than it actually is. It's patently self-serving in the worst way, a myth that is meant for them to feel comforted rather than confronted, and — again — I'm essentially sure that the people who are putting this forward are doing this in totally bad faith.

There are, again, many nuances to the "party switch" history, and nobody with any conscience would claim that either party has a great record on Civil Rights when taken on the whole of American history, because the United States does not have a great record on Civil Rights on the whole. Anyone who wants to believe that the problems of race are entirely the fault of the Republicans is misinformed at best. But the "there was never a party switch, the Republicans have always been the best party for Civil Rights" argument is totally wrong, and the fact that D'Souza and his ilk propagate deliberate falsehoods, even in the face of obvious corrections, says to me that they're just in it for the money.

There are legitimate conservative interpretations of all of this history, and plenty of solid but conservative historians whose interpretations one might disagree with, but respect as being put forward in sincerity. D'Souza et al. are not that, and they should be shunned and ignored. They do not care about the truth of the matter in the slightest — that is not their goal or their game.