The idea is to create a stable state with modern technology that still has widespread chattel slavery without any racial discrimination. I'm not saying the slaves can't be educated or do skilled labour, but they must be owned by someone else and have no rights but what their owners give them.
Of course any state in OTL who had a system like that would end up isolated with embargoes, so it might be easier to make it a global trend, but its not nessesary as long as the state has the same level of development as a first world country.