The thing is that engineers produce and maintain documents. Specifically they produce source documents from which the end product has been derived.

That's exactly what a coder does.

There are some fields (draftsman, typist, others?) of people who created fine documents based on vague documents from engineers, architects etc. So in principle you could have a similar distinction between software archtects and coders. But it is exactly those document-gruntwork fields which have been transformed most by computers.