The problem with that definition is that it assumes all groups contribute equally to the larger collective. Or at least that if one group contributes less, it is entirely because the other groups have already disadvantaged it in some way.
There are a large number of examples where this is simply false.
That definition makes no assumption about a groups contribution; as the definition is indifferent of the socio-economic system at hand (free-market, closed market, communal, etc) if the distribution of privilege and goods is different for individuals depending on race then there is a system of racism at hand.
So if 1 racial demographic group does better than another group, and they profit (in some way related to privileged) from this, while the other group does not, how is this racism?
There are a large number of examples where this is simply false.