[AnthonyMouse]

>Trading the Apple for the Orange directly (bartering) is clearly more efficient than A and B both trading for dollars and then trading their dollars for the good they want.

This is theoretically true, but it wrongly assumes that the inefficiency is meaningful. We're talking about computers here. It all gets automated anyway. And if the efficiency is utterly trivial then it can't balance any nontrivial amount of currency manipulation.

[argumentum]

Sure, that's why I used the word theoretical myself, but my hunch is that it's not trivial for the reason that it's a really tiny basket of goods we're talking about.

I even think it's not trivial if your market is restricted to say, 25% of the general market. But in this case the restriction is to a tiny percentage of the complete basket of goods, so (as an amateur) my guess is it's significant.