On the historical stratification of buddhist doctrine on the evidence of the early buddhist texts

This is categotrically untrue.
It is even categorically untrue of the pali canon, let alone my imaginary “ideal” canon of overlapping pali and chinese.

For a mostly Pali centric analysis of exactly how often and in which books aggregates material actually occurs, see:

This is not the whole story of course, for that a genuine and robust analysis of jhana/sekkha and anatta/aggregates would need to be placed side by side, which is what I intend to do in the OP

This is true of the Pali, and the evidence from the Chinese is yet another example of why its probable that the original M lacked many of the S style discourses originally.