It's not necessarily training and methods. Any environmental issue would create the same situation (curriculum selection, normative bias into testable results, etc), as would a self reinforcing cycle of undervaluing the professionals and competent people running away from the undervalued profession.

I disagree with the parent post and do not dismiss your suggestion, but no, that needn't be the only cause. The profession itself may be disincentivized in a number of ways against bringing in capable people.

Yes, I agree completely. Though I would emphasise that teaching universally bad only when compared to what is achieveable from tightly scripted presentations. I think the actual task of teaching flawlessly while "winging it" is extremely extremely difficult, and beyond at least 98% of the general population, even positing a good working environment.