Not quite; there seems an implicit claim that oppressiveness exists along a gradient which, I can hardly resist observing, correlates closely with the average s

Not quite; there seems an implicit claim that oppressiveness exists along a gradient which, I can hardly resist observing, correlates closely with the average skin tone of those who employ a given dialect. On one end of this gradient, Wallace's "Standard White English" oppresses basically everyone on the planet save its few most fluent speakers; on the other, I've never seen anyone even try to make a claim of oppressiveness on behalf of, for example, AAVE.