...So this wasn't really a smear compromise based on telling slaves they aren't worth anything... it was actually beneficial for the slave.
not really, but it was beneficial for those states that allowed slavery because it gave them a larger number of representatives than they would have had if the slaves weren't counted at all
Because the north was so much more populous, it would have had a clear majority if the slaves had not counted at all - - who knows how things might have been different if that had been the case.