However, in most case, each of those steps resulted in a useful service or product.

I dunno if I'd say that, really. "useful service or product" is inferring a lot about the context in which these transactions are done, it doesn't really open up the box, there. Is gambling a useful service to have access to, for instance? What about, say, setting everyone about buying a big suburban house, a car, running out a ton of asphalt to these places, putting out utilities to them that are both financially insolvent in the abstract and also take up too many resources for what they are? Like, I dunno, if we're considering the alternatives, there, which incur much less consumption, and thus, much less trade, the alternatives that cost a whole lot less, I would say that the idea that this is a useful measurement really at all begins to totally fall apart. I dunno. I maybe wonder if, say, free healthcare might be thought to decrease the GDP of a country simply because less money is being thrown around.