It’s not about individual responsibility, it is about the structural inequities that persist. No one is suggesting that living descendants are personally responsible. It is perfectly reasonable to point out that they are personally profiting.
I’d love to see that email where she tries to draw comparisons with the treatment of Victorian housewives. There is a lot to say about that but hard to know where to start without knowing exactly what she said. But if, for example, she thinks it is a good thing that women can now inherit property, she needs to think about how redressing that sort of imbalance is possible when the structural inequity is between and not within families. Taking the (imagined) point to its logical conclusion, her wealth belongs to the descendants of the enslaved people who created it but were prevented from owning it.