Yet this is part correct, part wrong. Indeed every industry has some unique challenges that are not directly solvable. However, while a cast is absurdly expensive, the problem is being solved in large part by software in the FDM (3D printing) space and it's changing how things are built.

edit: this doesn't invalidate the OP thesis, which I strongly agree with. Except that it's not just engineers, this is a more general thing across many fields.

Do you work in this field or are you just reading that? I’ve been out of the game for over five years now, but as far as I can tell from people I know still in that world, if you’re going to make more than like … 3 of a part, casting is going to be much cheaper. And while you can do some prototyping on 3d prints, the nature of the material winds up different from a cast part.

That's totally untrue. You clearly do not have any experience designing, building, manufacturing, testing, and certifying either cast metal or PBF parts. BTW, PBF is powerbed fusion and it is how you make 3D printed metal parts. FDM is a plastic manufacturing process and has nothing at all to do with replacing metal castings.

For a certain aircraft part that I designed, that measured approximately 16"x8"x10", if you needed up to 12 of them it was cheapest to 3D print them using powerbed fusion from AlSi10Mg, but with a 25% weight penalty due to the lower mechanical properties of 3D printed aluminum compared to cast. If you needed between 12 and 50 of them, it was cheapest to use 3D printing to make a wax preform then use the preform to make a traditional metal investment casting from A356. For more than 50 of them, it was cheapest to invest in permanent closed die tooling.

Other than for prototyping and extremely low volume production, additive has been a total flop for real-world manufacturing, and has not at all lived up to any of it's lofty promises.