any time a problem of this magnitude hasn't been solved AND you think the answer is 'blindingly obvious', consider that you don't fully grok the problem. I've been in healthcare analytics for 10+ years and it's incredibly difficult to measure outcomes. Take your example of 3 year outcomes, are you saying that the entire reason why someone is alive is because of the hospital they went to 3 years ago? There are so many confounding variables that even trying to measure outcomes 90 days out is difficult.
On top of that, the other commenter mentioned the unintended consequences of simplistic measurements like the one you describe. Look at measuring patient satisfaction - 'what could possibly be wrong with measuring patient satisfaction', people say! hold docs/hospitals/etc. accountable. but when you look at the data, patient satisfaction scores are weakly correlated with evidence based care and healthy outcomes but it is strongly correlated with things like how much time the patient sat in the waiting room or if the doctor prescribed them a medication.
On top of that, the other commenter mentioned the unintended consequences of simplistic measurements like the one you describe. Look at measuring patient satisfaction - 'what could possibly be wrong with measuring patient satisfaction', people say! hold docs/hospitals/etc. accountable. but when you look at the data, patient satisfaction scores are weakly correlated with evidence based care and healthy outcomes but it is strongly correlated with things like how much time the patient sat in the waiting room or if the doctor prescribed them a medication.