No, "the masses" have never believed that. Not even Trump's most rabid opponents believe that he invented racism, for instance, merely that he is more openly racist than his predecessors, and that he is more openly supported by racists than his predecessors.

The point is, the (white) "liberal" left has been sitting on it's hands, head in the sand, believing there has been sufficient progress. They did well to sell that (lie).

Now Trump shows up and suddening all hell is breaking lose? Nah. It's been there all along; swept under the rug. So rather than admit "yeah we underestimated the lack of progress" Trump & Co get the blame. This is fake history and it conpletely ignores real history.

Note: I'm not a Trump supporter. He's not my type of leadership. But we can't solve the right problems the right way if we are in complete denial about the root of those problems. The left's just-blame-Trump strategy is a great distraction. It's also, ultimately, a another step in the wrong direction.