It hurts the victimhood narrative - but slavery produced very little real “wealth.”
Like all state-controlled or forced labor rackets, it can not compete in efficiency, output or even pricing with free labor markets. Yes - it benefits those few in control of the monopoly, but it penalizes everyone else.
If southern slavery was economically efficient, the south would have won the Civil War. Brazil would be a world super-power
Came D@mn close to winning, and that's despite the North having 4 times the population to draw soldiers from.
I think your theory is flawed. It may be correct, but the South's losing doesn't provide proof that it is. Any army that is outnumbered 4 to 1 tends to lose.