I understand your points and I do sympathise with your position. When I went through well known UK modular school (which had an excellent reputation) pretty much every CPL/IR instructor was an ex PPL instructor who had moved up the ladder. None had any line flying or multi-crew experience other than one who was an ex-FE. I must say that we all thought they were very good instructors and I never heard any complaints.
I guess at some point the training pipeline is going to grind to a halt.