It's Confederate History Month in Dixie

[Beskar]

The slaves already did the work on those plantations, why shouldn't they be entitled to keep what they produced?

I read this statement as Serfdom, basically. The slaves become peasants and they work the lands and they keep what they produce, but they pay/rent or give a certain percentage of the crop to the owner. Another way of doing it would be the employ the slaves as labourers, so they can continue working the land as workers, not as a slave.

And thanks for the pre-edit correction.

Had me confused at first at what you meant, then I remembered I made a comment that it wouldn't be Marxism as the state would just take the land and it wouldn't be owned by anyone.