You're absolutely correct!
Poetics is descriptive rather than prescriptive. That was his intent when he wrote it. It's the millions of writers and theorists after him that have converted those obseervations into prescriptive applications.
Dramatica is also descriptive (Isn't that what theory does, describe a phenomenon?). The struggle is in the prescriptive side of the theory.
Prescriptive theory is often based on descriptive theory. I'd venture to say that Subtext is trying to fill this void. Great!
Isn't that the whole point of your thread about the RST? Aren't you trying to find something specifically prescriptive based on something descriptive and general?
I'm not taking anything away from the incredible minds who wrote this theory. I'd classify it as brilliant, but it obviously has been influenced by earlier efforts. If you are going to write a theory about story, then you are probably going to look at the material out there. Melanie has called Aristotle a genius, and rightly so. Takes one to know one I guess.
For example, look at a few D. Swain quotes (also drawing greatly from Aristotle):
"Once you’ve gained sufficient skill, however, you can make the disaster potential and not actual."
Goals are of two kinds: goals of achievement, and goals of resistance. The first is explicit, as in our examples; the second, implicit.
"The future should always hinge on each scene’s outcome—that is, its disaster."
"Similarly, you can reverse the disaster, as it were. Instead of ending your scene on a down-beat note... you play the other side of the record and set him up to ride for a fall."
"What is a feeling?... It’s a subjective awareness of the ebb and flow of inner tensions, expressing itself in a reaction."
The power of the subconscious is an amazing thing. We get ideas from so many different places. We find pieces of what we need and fill in the blanks for what wasn't available.
He didn't. He came up with Poetics.
Further, you could say the creators of Dramatica didnt come up with anything besides Dramatica. Both theories describe a process (storytelling) that existed before them.
So, could you elaborate on your point?