The reason black is used as the stand in example is because it forces you (assuming you’re not racist) to see the issue with generalizations that you’re ignoring because the original group is culturally ok to hate, while black people are not culturally ok to hate. It’s to make you see your own prejudices, and to do so uses the most glaring example that has been widely publicised since the 60s at least. Could they slot in Inuit instead of Black? Sure, but that doesn’t have the same impact when you read it. And you’re supposed to be upset about it, but not at those forcing you to look inward with the comparison, rather at yourself and those that make you ok with holding your prejudices.
The reason black is used as the stand in example is because it forces you (assuming you’re not racist) to see the issue with generalizations that you’re ignoring because the original group is culturally ok to hate, while black people are not culturally ok to hate. It’s to make you see your own prejudices, and to do so uses the most glaring example that has been widely publicised since the 60s at least. Could they slot in Inuit instead of Black? Sure, but that doesn’t have the same impact when you read it. And you’re supposed to be upset about it, but not at those forcing you to look inward with the comparison, rather at yourself and those that make you ok with holding your prejudices.