patprimmer puts things quite well. To converse i.e. cooperate appears a major aspect, besides buying in the best deal (best quality/price ratio, not cheapest) integrated by the advice that one should do his work well instead of engaging in non-indicated interference with that what others are supposed to work out.
That enginners should do engineering seems obvious, but isn't, as a degree course doesn't secure to qualify one, it merely shows that you are a more or less smart guy wrt maths/physics, with picking up concepts, learning, which is a good ingredient anyway. But you need practical insight in design, manufacturing, organisational skills, the ability to cope with timing restraints, stress too - and, probably providing you the former skills with ease, luck to meet the right people, basically it takes good practising engineers as examples to 'build' good engineers, on top of the academic achivement.
There should be, in general, a engineer in charge for technical products development, one who is able to supervise non-degree designers and, were indicated provide guidance, advice, such as to avoid that things get unproffesional.
One doesn't need a degree to be a good designer or mechanics, workshop person, but at some level there need be a engineer to sign responsible, to establish, provide a retraceable responsability chain - and if you have some of the good engineers at critical, strategic points in design, manufacturing etc. that pays dividends.