Reports built on KPIs are like having 10 different managers telling you 10 different, entirely unrelated stories and leaving you to figure out what they mean when you put them together. That might be life, but it doesn't have to be reporting.
Understanding the system -- the interrelationship between parts -- is fundamentally different and more important than understanding the state of any single volumetric.
It turns out that a change in any single variable in a complex system can always be explained in a variety of ways -- some of which would be interpreted as positive and some as negative. It doesn't matter if the metric is site satisfaction, revenue, conversion rate, or traffic. The possibility of multiple explanations makes it impossible to extract either meaning or actionability from single KPIs.
