First, let me simply call it minimalism (min) if that’s okay. If you want to spell out the post thats fine, but I’m already getting tired of typing.
I believe there should be a distinction not necessarily between min and postmin, but between minimal and PM, the styles of both in which they vary. I think since rhythmic min became most popular out of all the min (the later min that is) that the earlier min has been left out or counted as a misplaced genre. Feldman and Satie (help me name others) and their minimalist works are valid and yet we probably tend to think of their stuff more as simply “something else” (Feldman’s case, but Satie of course impressionism and forgetting minimalism discovery), to that effect at least, instead of their ties to minimalism.
Pure rhythmic minimalism seems to have crowded the stage as of late (last 20 years +). What about those other minimalists?