That means Turing-completness enable to do more stuff and more efficiently than Turing-incompletness, am i right?
Only to do more stuff. Efficiency doesn't matter.
Also I think I get why it's important for a DAC Platform (where you build DAC on top of it), but why a DAC alone should be bother with Turing-completness? Since a DAC can probably be program from the start to be able to do what it supposed to do in a efficient way, even with Turing-incompletness (e.g. Bitcoin).
I doubt it's possible to create a DAC in a Turing-incomplete language. But u should try.