The difference here is reliability. Commodity kit is generally reliable, just slower; whereas cheap 3d printers are more likely to fail a print/produce junk.
Meanwhile the assembly line and workers expensively wait for the assembly jig to be printed. And the contract due date doesn't automagically move out a day because you had a printing problem, so now you're paying (more?) overtime once you finally get a working jig.
There is a solution to that, when your labor and capital costs are huge but the cheap printer is 1/10th the cost of the fancy printer... simply install and use 3, 4, maybe 5 cheap printers, keep the best print, and pocket the savings.
Yeah, but 3D printers are also really slow. The part in the article took 18 hours (on both printers) and in my lab we've had similar experiences.
Not sure where the break-even point is, but the cost of a failed print is pretty high in terms of sunk time for most prints. On an industrial scale, a machine that prints correctly 99% of the time might be a better investment than two that print say 75% of the time.