An example (via encyclopedia Americana) of why your statement is an over simplification and not true follows:
The Second Bank of the U.S (true it was privately held) was supported stongly by the north and the federal government as it dominated the U.S. banking industry....."Because it consumed rather than produced manufactured goods" the south opposed the protective tarrif involving the bank as the south was anxious for credit not required by the north; the north was almost totally diversified.
The tarrif was no trite issue and was an integral piece, including slavery and the other resons detailed, of the decision by the south to leave the union.
I think your belief that slavery, and only slavery, was the singular reason for the Civil War is an over simplification of reality. Accordingly, I think we have run this thing to the wall and I wish you well.
No one made the south focus on cash crops as opposed to industry. Factories COULD have been built there. There was a move to "bring the spindles to the cotton", but it died aborning because the slave power didn't like the idea. They wanted everyone besides themselves to stay in peonage to them.
Walt
I'm a real southern gentleman myself.
Walt