Domain-specific knowledge, having no relation to software engineering per se, is a necessary skill set. The best analogy I can find, if not a tired one, is the equivalence of software engineering to tool-and-die making. In prior generations where manufacturing was king, it was a necessary operational skill set in order to produce things at scale, yet is much less (if no longer) relevant in the age of additive or subt…
Also 3D printing is good at making unique objects, but if you want to make ten thousand of the same object, you definitely need someone who knows the "old" ways. They're not irrelevant at all. And you can even use a 3D printer to help make your tools and dies.