If you're a private enterprise, anything you do can be reasonably related to money (revenue, profit, long term forecast etc.), and we have ample tools to measure performance, align incentives and evaluate risk over the money-abstraction. This works because money flows through the whole process and partakes in every transaction.
Academic pursuits are, monetarily speaking, money sinks. They might be worthwhile investments, but only so far as they deliver patents or attract grants. Academic professionals want to advance the state of the art, and only small parts of that work is applicable to the money-abstraction.
In order to prevent Science(TM) from grinding to a halt, we replace Money with some other measurable so we can apply our existing tools and make risk-assessment before granting money to academics who will (most certainly) spend every last cent of it to indulge their pursuits. We chose measurables in a trade-off between academic freedom + infinite spending and academic constraints + finite spending, because the supply of Science(TM) is practically unbounded.
I'm stating the obvious here in order to ask the question: What is the gosh-darned alternative?