The U.S. isn’t a democracy per se and never was.
It’s a democratic republic.
That is true.
I would speculate that when Du Bois writes about Democracy being dead in the United States, he specifically is referring to the democratic elements of our republic, i.e. freedom of choice, popular sovereignty.
In theory, if both candidates represented the same long term (((interests))) behind closed doors, and those (((interests))) were in no way beholden to the will of the people, then it would accurate to say the process is no longer democratic.
Agreed