All absolute true I think. My only addition is that in my educational experience, a number of times someone would came in to teach with an entirely practical a

All absolute true I think. My only addition is that in my educational experience, a number of times someone would came in to teach with an entirely practical and non-academic background, and it was always a clear and tangible breath of fresh air. Their approach, priorities, clarifications, honesty and insights always had a comparative sense of vitality and importance about them, irrespective of how good a teacher they were in the normal sense. Your point still holds about how to assess, which as you point out, is its own thing. But it also doesn't exclude the possibility of recognising and providing the value of education from those outside of the education/academic system, however hard that value may be to measure.