It would be interesting to have a reasonable, objective discussion on the issue of slavery’s affect on the US, but without the hyperbole and agenda driven absurdity of the living confederacy. So, it’s not going to happen soon...
Henry Clay’s nephew, an abolitionist, criticized slavery on purely economic terms. He claimed that slavery prevented the economic development of the South. The Civil War certainly did not help.
It was cheaper for a capitalist in the South to invest in slaves than machinery and the availibility of slaves (or illegal immigrants today) depressed wages at the low end of the pay scale.