The fact is, breath work is a significant contributor to overall IS development. Whether the fascia gets worked and strengthened as a result is by-the-by.
If people want to get into the nitty gritty, then perhaps a relevant point of discussion might be the differences (or similarities) in the various breath methods themselves.
Aye and there's the rub. The "fascia" and the jin/kokyu are interdependent, but they work as a whole in the full banana. In the not-so-full banana breath is just a conditioner of fascia and fascia is an adjunct to the the process (including dantien/hara usage). So 'various breath methods' won't really tell the story by itself, but you don't really get full internal power without practicing correct breath methods. And they take a while to show results.