You've nailed it. This is why PC Revisionists attack the South by trying to claim "it was all about slavery" when the facts make it clear it was not. This is an effort to smear the South because the South has always stood for decentralized power, limited government, limited spending and balanced budgets. This is all anathema to Leftists. If only they can discredit the South then they can discredit all of the above.
Thus starting in the 1980s as that 60s generation was starting to gain ascendancy in their long march through the institutions, the 60s Leftists in Academia revived wartime propaganda that had long since been discredited - yes even in Academia itself - and have fanatically pushed this as though it were religious dogma ever since.