Yield is an important measurement though. Nutrition is a fine metric, but some things grown in permaculture are not nutritive. They may grow nitrogen-fixers, shade plants, fodder, etc. These don't provide 'yield', but reduce outside inputs.
The most important thing is to change how you think about yield. Yield/acre needs to take into account how much outside inputs are involved (trucked in fertilizers, mechanical inputs, etc).
It's absolutely correct to measure how we're doing. It's tricky when the units of measurement are not the same. It's harder still where there are so many types of soil/climate conditions and so many types of output to measure. But we can't just ignore output if we want to improve or give prospective adopters some idea of risk (they are literally betting their farms on it afterall).
The most important thing is to change how you think about yield. Yield/acre needs to take into account how much outside inputs are involved (trucked in fertilizers, mechanical inputs, etc).
It's absolutely correct to measure how we're doing. It's tricky when the units of measurement are not the same. It's harder still where there are so many types of soil/climate conditions and so many types of output to measure. But we can't just ignore output if we want to improve or give prospective adopters some idea of risk (they are literally betting their farms on it afterall).