I... Really DR?
Really? I know it's not your history but it's pretty easy to sort out. The South seceded in VERY large part due to slavery. The justification of said slavery was expressed in the language and philosophy of American White Supremacy. The flag of the Confederacy, traitors to my nation I would add, was the flag of a political entity based upon slavery and racist ideology no matter how anyone tries to frame it these days. I refer you to here:
https://en.wikipedia.org/wiki/Cornerstone_Speech
This speech by the Confederate Vice President contains this passage...
"Our new government is founded upon exactly the opposite ideas; its foundations are laid, its cornerstone rests, upon the great truth that the negro is not equal to the white man; that slavery, subordination to the superior race, is his natural and normal condition. This, our new government, is the first, in the history of the world, based upon this great physical, philosophical, and moral truth. This truth has been slow in the process of its development, like all other truths in the various departments of science."
Racism was and I would argue is deeply baked into the culture of the South of the U.S. Resentment against their loss after attempting to break away from the U.S. simmered long after the war and frankly, well past Reconstruction, through the early 20th Century, past the Civil Rights era and into the modern era. The saying "The South Will Rise Again" has at it's core an implicit threat against non-whites. It is no coincidence that White Power groups such as the Klan (I assume you've heard of them, but if not:
https://en.wikipedia.org/wiki/Ku_Klux_Klan) are associated with the flag of the Confederacy, as they were formed during the reconstruction era. The culture of Jim Crow (again... If you aren't familiar with the term:
https://en.wikipedia.org/wiki/Jim_Crow_laws ) was just an extension of the fallen Confederacy's philosophical outlook on what it thought America should be. Now... I grew up with the DUKES OF HAZZARD as well, but then... I'm a Hispanic from New York City. Now, imagine you grew up African-American in the South of the U.S. and the flag is everywhere. The flag of the political entity whose objectives in it's existence were to keep your ancestors in bondage and oppressed in perpetuity, meaning to that entity it would just be fine for you and your children and your children's children to be human chattel with no real rights? Is it starting to dawn on you the implications of the flag? If it supposedly represents "heritage, not hate" then one must look at said heritage and realize it is a heritage OF hate. The flag and the defense and celebration of it has implications and none of them are positive. Also... It's doesn't take a lot of digging to find any of this out.
No, officially the flag is not "banned" as the Nazi one is in Germany.