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Training, Supervision, Experience, Competence have got nothing what so ever to do with the airworthiness of an Aircraft. Airworthiness is for engineers only.
You are of course entitled to your opinion as to what the regulations should say, but until they do.............
The reason why all these components are lumped together is because airworthiness is about Safety. Engineers contribute to that safety.
If you are still "in", raise a MF765 (Unsatisfactory Feature Report) on JSP553 suggesting your proposed changes.
But, and I'll give you this gladly, your stance is far better than the MoD(PE) 2 Star who said "This is of no concern to MoD(PE)".