It seems to me like the American left is trying to incite another Civil War by removing one of the original terms of the peace between the North and South.
As I recall from high school, one of the prime features of the South's surrender during the Civil War and the following postwar period was the notion of "defeat without dishonor." That means letting the defeated Southerners bury and honor their dead, fly the rebel flag and retain other culturally significant artifacts of their fallen Confederacy, and not imprisoning their soldiers.
This entire movement seeks to upend that and, indeed, pervert it by shaming millions of Southerners today for abuses conducted by their ancestors. Abuses which neither the people who want the statues to remain or the people who want them taken down have any connection with. The left wants to punish people in places like Georgia and Virginia for their original sin of simply being Georgians and Virginians.
This constant, unabated demonizing and ridiculing of Southern people threatens this peace. If you tear down their monuments, prohibit them to fly their flags, and shame them at every opportunity, they will lose the desire to remain a part of the Union and seek secession again.