Great question and, unfortunately, I don't have a great answer. I think, however, that an economic value judgment produced in a smaller community that creates its own currency is more accurate than, say, a central bank doing it on the basis of aggregate transactions for the whole economy. And, in the case of blogging, the central bank would traditionally not even consider it economic activity because it is unpaid. Can the smaller group be wrong? Of course. Can they be controlled by influential individuals? Yes. All human groups can have these flaws. The model here is still being tested but it looks like progress and decentralization is usually a good thing.