Back when I was in high school, I got to talking with some of my classmates about what our respective nationalities were. As part of it, I noted that I had German on both sides of my family, and that my maternal grandmother was a war bride. The class troll overheard us, and for the rest of the semester he would make Nazi jokes whenever he saw me.
Similarly, if you look at anti-Mormon writings you'll see that they invariably either wave polygamy around as a bloody shirt or wave Mountain Meadows (in which a group of Utah state militia that had been panicked by word of an invasion partnered with a group of Native Americans to annihilate a wagon train seen as a mutual threat) as a bloody shirt.
What we're seeing here is the same basic principle: there are those who legitimately believe that due to past actions, entire cultures, religions, and ethnic groups need to be made to feel shamed
forever, with no chance of redemption. Being a member of this group, even if they were simply born into it, is tantamount to Original Sin, and so the person must be made to wallow in regret and penance for their entire life.
This is what people refer to when they talk about "Cancel Culture" and how horrifically evil it is: there's no chance for a person to be seen as a person, let alone show that whatever people think about them is incorrect or attempt to atone for any legitimate misdeeds.
In this case, the "good and proper" crowd has decided that the South is, and forever will be, linked with slavery and oppression, and so anyone who resides in the South and fails to present themselves as either a victim or proper penitent must be regarded as sub-human.
Simply put, a lot of what we're seeing these days with Confederate flags and other symbols becoming more visible is push-back, people coming to feel that they themselves are being attacked and desiring to push back by whatever means they feel appropriate.
Consider, for example, a situation that happened here in Texas a few years ago. The city of Austin decided to re-name Robert E. Lee Elementary School, and opened it up to the public for suggestions.
School Asks for New Name, the Internet Answers 'Schoolie McSchoolface'
By Snopes, the #2 suggestion was to simply leave the name as it is.
You can read for yourself the other suggestions people had, although the Snopes article omits the fact that "Bruce Lee Elementary" and "John Cena Elementary" had a few nominations as well.
Basically, most of the people who responded either wanted the name to stay the same, proposed clearly unacceptable names as a protest, or proposed unrealistic names as a troll job.