I think it would be odd to say that macroeconomics only is relevant to what government does, because it's relevant to understanding the world. Suppose you had a really good theory of macroeconomics, which let you make predictions about what happenned next year. Well, if you predict that next year there will be higher unemployment, that might be a good reason not to quit your job this year, for example. That would be an example of a perfectly private decision affected by your macroeconomics predictions.

David Friedman