Without the fascia, the muscle would flop around loosely (assuming there was still a nerve fiber attached to it). And I do think that the fascial system enables the whole muscle system to share information (in a manner of speaking). So I do think we'd be leaving out a lot of important information to omit the fascia from the discussion.
Sure, they are of course an important part of the muscular system. But by analogy, look at the mitochrondria. Without them, we'd be corpses. They can even be trained individually in certain aspects. And at the high levels of sports, drugs that enhance their function are essential to stay competitive. But would training only the functions of the mitochrondria result in complete athleticism? Now, surely knowing about the mitochondria would inform how one went about their athletic training, but would it decide the entirety of their athletic training? Would it be the underlying theory of how they trained... everything?
So, in practical terms, is isolating out one structural component of the muscle, while ignoring the other aspects of the contractile machinery, useful as an overarching strategy for the practice of martial arts? Would it optimize the performance of the whole system? ... Or is there something more at work here (and being worked on) than simply focusing on fascia can explain? Can it provide me with a useful predictive theory of how to measure and train these aspects?