Oh, gee Fionn! I don't know what you and Ms. Garvey are arguing about, and don't particularly care. Very likely I agree with you and not with Mary. But "maybe they didn't build their wealth on the backs of slave labor"?!!! That is truly gratuitous. It is not enlightening. It does not make any particular point. It serves no purpose but to make the other party angry. It lowers my opinion of you.
You often say say stuff like that. It gives the impression that you are mean-spirited and inclined to take cheap shots. Is that the reputation you are aiming for?