Because in many cases human engineers will directly fight the mere suggestion of measuring anything in order to achieve self-satisfying desires like easy, clean, clear, safe, and so on. Its not about what the developers want. It's only about the product. Human engineers that put themselves before the product are an ethical liability. Ethical failures are more the norm than the contrary in software, and one way to fix that is to hold people (entire teams) liable for failures to perform above certain established baselines.

For me its all about lowering regression and internal execution speed at all steps as much as possible, because I would rather do something else with my time than repeat myself on the same slow failures over and over. Getting my time back for personal use is a win for me and it allows the employer to ship a faster and more durable product.