By the time you've actually described what reference someone is tracking (or even a sub-reference like "sexiness") and how observations are converted into a format capable of being compared, you've already solved the problem

Yes, and that's precisely what's useful. That is, it identifies that to solve anyone's problems, you need only identify the reference values, and find a way to reorganize the control system to either set new reference values or have another behavior that changes the outside world to cause the new reference to be reached. (This is essentially the same idea as Robert Fritz's structural consulting, except that Fritz's model is labeled as being about "decisions" rather than "reference values".)

The main difference between PCT and other Things That Work is that PCT is a testable scientific hypothesis that includes many specific predictions of functional operations in the brain and nervous system that would reductionistically explain how the various Things That Work, do so.