The assumption underlying this analysis is that no merit exists outside of subjective value judgement. Furthermore, subjective value judgments are biased in favor of the existing privileged groups. Do I have that about right?
You can't. Merit -- including "success" or "accomplishment" -- is always a subjective value judgement. Even if there is an objective measure, the evaluation of the measure as something meaningful to measure (i.e., that the measure is one of merit or success) is a subjective value judgement.
And the dominant group in society is, pretty much by definition, the one whose judgement is most influential.
Then what is the viable alternative to achieving merit in the judgement of that group?