The reason that they needed to set up such a complicated analogy is because they needed a way to justify a hand-wavey fitness function of "extensibility/modular

The reason that they needed to set up such a complicated analogy is because they needed a way to justify a hand-wavey fitness function of "extensibility/modularity" instead of the much simpler and more useful "does this thing actually survive?" Despite (or, as you argue, because of) its adaptibility, the answer to that question is empirically "no."