He’s right... While slavery has been the single dumbed down reason given, but the civil war was far more than just about abolition.
If it was, tell me why the Union had Slave states, and the Emancipation Proclamation did free a single slave in those states?
Go read up on the tariff of abomination, and the nullifier movement etc.
Go read the 528 prior posts. The reasons why you are wrong are all in there.
The reason it's "the single dumbed down reason given" is it's the single biggest reason given, if not the only reason given, in Deep South "Reasons for Secession" documents.
So the difference between real history and Lost Cause myth is that real historians take the 1861 secessionists at the own words, whereas mythologizers insist that wasn't the "real reason" and concoct other issues they claim were more important.