How do you establish competency when the people you are measuring are the people putting the test on, grading it, choosing its metrics, and who define competency as “the thing Im doing right now, thank you very much”?
Youre arguing for a vapid ideal that relies on politicians to not be politicians while they appraise themselves and one another.
You basically want to give them a political cudgel to weaponize against political enemies because the concept gives you the warm and fuzzies.