Measuring a big system might be useful if you are interested in this information. However, steering the big system by looking at the big statistics while ignor

Measuring a big system might be useful if you are interested in this information. However, steering the big system by looking at the big statistics while ignoring its much more deterministic effects on parts is both, an oversimplification and common practice. Just think of a tax where they talk about future income streams for government but totally deny the costs (especially for complex taxations or ambiguous legislation). Or changes to the way GDP is calculated. Or "economical stimulation" via war.