I don't want to get very involved in this conversation (I think people should speculate and think in all sorts of directions), but I'm not sure voluntary control of fascia and contractable fascia, etc., is necessarily the right answer to the basic question about how things work. No real research has been done on this aspect of qi (that I know about), but I know some of the effects first hand and I can postulate several other mechanism that would explain the effects. I.e., the assumption that contractible fascia is a basic answer isn't the basket I'd put all my eggs into.
There was never any implication that voluntary control of fascia is the whole or "right" answer to "how things work." But, I would not dismiss it as one factor in a complex process. That connective tissues (fascia, tendons) are not mere inert organic substances, and may be playing a role in subtle machinations we can learn to do, but which are not commonly known, is a fascinating topic of exploration and study.
Of course, any understanding we derive from such studies won't help in the least in learning how to create, harness and utilize any physical skills, but it would be pretty cool to know what's going on "inside."