Why is science just a starting point and not an end point?

Science is a methodology that allows you to detect patterns in data. 

Once the patterns are validated and determined useful, then the science gets applied. Engineers trained to apply science to solve problems do that.  Then others benefit from the fruit of their labors.

That's how it works.  Plain and simple

Let's take a trip back to 7th grade... the scientific method is:

• Make an observation.
• Ask a question.
• Form a hypothesis, or testable explanation.
• Make a prediction based on the hypothesis.
• Test the prediction.
• Iterate: use the results to make new hypotheses or predictions

Science cannot take a look through a telescope or have a bias opinion or distort facts to prove false theories.  Those are human activities. 

In term of sound, you can test for distortion, frequency response, rolloff, stored energy, and many other things that can indicate you have a problem.  The missing elements are time and perception or space between the sound that isn't measurable.   

So... to me science isn't letting you down it's your expectation of science.  

"science isn't letting you down it's your expectation of science"
+1

"science isn't letting you down it's your expectation of science"

Surely science should be able to show where sound is being corrupted or deviating from a source? Science cannot predict how humans perceive sound, but it should be able to measure the performance of equipment!

Scientific methods can be used to measure all sorts of performance criteria- volts, amps, volume, etc. Human beings however listen and rate performance based on their own personal evaluations of all of these combined. Scientific methods can be used to try and determine things like the weighting a particular listener gives each measurement, but it would be an inference based on their actual choices. This is all a long-winded explanation because you said, "science cannot predict how humans perceive sound" which is correct. But you then finish the sentence with, "but should be able to measure the performance of equipment!"

But science can. The discipline you seek is called logic or deductive reasoning. In it you will learn to avoid combining unrelated clauses as if they lead to a conclusion. They don't. They are unrelated. They lead to naught.