I saw Birth of a Nation while at NYU Film school. Seeing it was a rite of passage but the introduction to the film was always along the lines of "this is a filmmaker who was ahead of his time in terms of technique and way behind the times in terms of his racism and hatred." Discussion afterwards was heated.
I hope your excellent piece gets more people to be aware of the history of stereotypes and hatred in this nation. The fim is cringeworthy and while it's easy to catch on YT, I started watching it and couldn't go any further. I agree that seeing it once was quite enough. Bravo on a really interesting exploration. Write on.