I'm still reading the article in The Atlantic (it's pretty long). The issue is that the expression "reparations for slavery" sounds as though one group of people is being punished for crimes they didn't commit, in order to create restitution for another group of people who are no longer here, or people who didn't directly suffer from slavery. The general idea makes some sense, but it doesn't work as a legal concept. For example, if a person was a predatory lender (regardless of the color of his skin), he could be punished for usury. If a person stole land or property, that person could be punished for theft and be forced to make repayment. If a person committed assault, he could be punished for that. That's normally how the legal system works. However, this assumes, of course, that the rule of law exists, while it sounds like the rule of law did not exist in Mississippi up until the 1970s, if that.
It might be relevant for the state of Mississippi and other southern states to create some type of reparations program for people affected by Jim Crow laws, or lack of other legal protections. In other words, just as the abuses were localized or regionalized, so would be the reparations. If you're saying, "I'm black, and therefore I should be given money or land," regardless of who you are, where you live, and whether you actually suffered abuse, that seems less likely to get traction.
I do think it is an idea that's worth discussing, just as it's worth discussing reparations for indigenous people who have been displaced by Western colonization and industrialization. But you would have to define who it applies to and how they were affected in a way that makes some sense.