Thank you for this thoughtful and well-reasoned opinion. I would also like to add a global take into the discussion. Who stands to benefit from the American people being both divided among white / black, male / female, old / young, and distrusting of the media? Certainly not anyone in America.
Not OP. When considering this line of thought, I think of meme's in the original sense of the word. So one could take a mildly-conspiratorial take on it and say that the "meme" itself stands to benefit from this sort of division rather than a nefarious agent or group. It's a self-feeding cycle because I would argue that this cause done in a bad/unfair way sows more racial/gender/etc division and as such creates more reason for itself to exist.