A second advance this document makes over existing ones is to recognize its own limitations. A whole section is devoted to “What is not covered by the Standards.” This turns out to be a lot, including teaching methods and the curriculum. But the concession is critical. The word “standards” has misled the public into thinking that these documents represent curriculum guides. Yet not even the best of the current state standards defines a curriculum. This document is, I believe, unique in stating that it is neither a curriculum nor a curriculum guide. Rather, it concedes explicitly that proficiency in reading and writing can only be achieved through a definite curriculum that is “coherently structured to develop rich content knowledge within and across grades.” This is a welcome acknowledgement that only a cumulative, grade-by-grade curriculum, focused on coherent content, can lead to the high level of literacy which the nation needs.
This is kind of like saying "What I like about this law is that there is a whole section in it devoted to explaining the difference between a law and a regulation. A lot of people get confused about this so it is helpful to embed a reminder in the law itself." Um... ok, but the professionals who use these documents (a category which does not include E.D. Hirsch) already know the difference.
And the reason "the public" are confused is mostly because of E.D. Hirsch and his colleagues who call for "rigorous content standards," which suggest that they are some kind of curriculum guides but which by my reading, aren't very different from the evil "skill-based" standards.
Also, that "only" is a crock -- plenty of people become highly proficient in reading and writing without a cumulative grade-by-grade curriculum. You might argue that on a systemic level, that is the only method of assuring proficiency in the most students, particularly those from impoverished homes who do not pick up rich academically-useful background knowledge informally, but it is not the "only" way.