The Purpose of the System Is What it Does

Scott Alexander over at ACX just put out a serious/fun essay  Come On, Obviously The Purpose Of A System Is Not What It Does 

But then what was it meant to apply to? Nobody uses the phrase in cases where it’s obviously true - for example, nobody says “The purpose of a system is what it does! Therefore, you must believe that the purpose of airlines is to transport people using planes!” It’s only used for galaxy-brained claims like “The purpose of a system is what it does! The police do a bad job solving crime, therefore the purpose of the police must be to tolerate crime, no matter what you gullible starry-eyed idealists who take the police’s story at face value might think!”

Here the correct response is that the police might try to solve crime, but fail - just as the Ukrainian military tries to win wars and fails, or a cancer hospital tries to cure every patient but sometimes fails. Given that this is not just possible but in fact incredibly common, what is left of the phrase “the purpose of a system is what it does”?

I commented there, referencing that Pournelle's Iron Law of Bureaucracy has some merit, but after working in a state hospital for over forty years I can confidently assert that it does not cover the territory. Pournelle was genuinely brilliant, but sometimes clever cynicism masquerades as wisdom.  Because it's easier. I have fallen into it many times, and still understand how sometimes these cynical things are just fun to say. 

Bureaucracies do become good at perpetuating themselves and move toward doing the easiest parts, but there is a limit.  Someone has to actually make many cans of beer or the brewery goes under. Also, even in the starry-eyed fields, new starry-eyed people enter every year want to do what the sign over the door claims.  Nor are these always fresh graduates.  Sometimes they are people who have gotten sick of other bureaucracies or systems but still hope to accomplish something like what they set out to do.  Doctors and engineers come to mind here.