I had to look it up. Chattel slavery is simply straight up slavery, and our conversation was regarding capitalism versus socialism. There is no defense for slavery. But as I said, slavery was also the lot of millions of peasants from France through eastern Europe into central Asia. Capitalism arguably led to the elimination of slavery in the northern US as a high growth capitalist financed industrial economy thrived , and was certainly a component of capitalism in the south. Neither fact discredits capitalism itself.
Capitalism, socialism and caste systems are still common and slavery still exists.