Nothing wrong with teaching theories. I was pleased to read about the tariff theory for Southern secession, as an example of how the mind sometimes works to try to put more benign veneers on unvarnished evil. And I am interested in learning more about critical race theory. Heck, some of it might have merit, and even if I end up believing, to go to the hyperbolic extreme, that it is all an attempt to create an alternative universe, to poison people's minds, that is still a learning experience. I also have more faith in the common sense of people to see through BS than some here and there and maybe everywhere, may have.
I do think all of this is probably over hyped. Much of our opinion maker class seems to get off on fomenting hysteria.
I have a theory, it's that gravity actually works in reverse and pulls us all up to the sky, but we're so fat that we stay on the ground anyway. It's called GMA's theory of anti-gravity. We should teach this to kids because it has just as much truth and evidence as the "lost cause" theory.
The southerners told us why they were going to secede, when they seceded they told us why they did it, they continued to tell us why they wanted to stay seceded while the war was happening, and after the war the big thing they complained about was the reason they seceded in the first place.
The Lost Cause "theory" didn't really catch on until the early 1900s.