In my opinion, the best argument for what is called "systemic racism" is the compound interest argument and it goes as follows. Due to a long history of racist policy, even if the policies have ended, disparities would persist because wealth is intergenerational, and past investments grew greatly in size. And banning blacks from owning certain properties, or getting certain jobs, means they have less to give their children, compared to whites. This strikes me as plausible.
I tried estimating the size of intergenerational wealth transfer and then compared it to the size of the black/white wealth gap. There are other effects of racism unaccounted by this, like black-owned property being less worthwhile due to antiblack sentiment. But I don't think this is relevant.
About 20% of people inherited wealth. The amount is usually 10k-50k, although some of it is much higher sometimes. I will assume that the average is $50,000 and that all those who inherited are white. I will also assume that the whole gap is due to racist policies.
To rectify this, you want to transfer about $50,000 to 20% of the black population or $10,000 to 100% of them. (10k is 20% of 50k). You can even play around with it and create a 1% of millionaires or something.
Regardless, this works up to be about 400 billion. There are 40 million US blacks, so this is $10,000 per person.
Unfortunately, the black/white wealth gap is a staggering $164,000. ($188,000 for whites and $24,000 for blacks). This wouldn't change it greatly.
In the Atlantic article, Coates says that we should take the entire difference in wealth and assume it's all due to racism, this is ridiculous and innumerate. I will ignore it.
Regardless, the small transfer might still be still worth it. Because calculating an amount and giving it to the aggrieved would greatly weaken many attempts to use past wrongdoings (e.g. Slavery) to justify much more destructive policies to rectify the issue. But it depends on convincing blacks that this is just and proper, which might prove difficult.
https://www.theatlantic.com/magazine/archive/2014/06/the-case-for-reparations/361631/
https://www.vox.com/the-highlight/22320272/inheritance-money-wealth-transfer-estate-tax
https://slatestarcodex.com/2014/05/26/compound-interest-is-the-least-powerful-force-in-the-universe/
https://www.vox.com/2014/5/23/5743056/you-can-be-a-beneficiary-of-racism-even-if-you-re-not-a-racist
https://www.brookings.edu/blog/up-front/2020/12/08/the-black-white-wealth-gap-left-black-households-more-vulnerable/
https://www.overcomingbias.com/2019/03/consider-reparations.html