Scalability as a KPI

One item that companies should do a better job with is understand departmental scalability.  Are the company grows, do each of the departments grow with the same scale?  Does finance not scale because of compliance and risk, or because of broken processes?  How do we know if we can't track Revenue / Departmental Headcount over time?

And if we do start to do a better job tracking metrics like this, doesn't this give us greater insight as to where the organization gets the most bang for the buck?  As well as give us a defensible rational to defend against empire building for personal reasons?