There tends to be a lot of demonizing and blaming the victim in general on HN for people who won't learn new skills. I've coasted by for a couple decades really only having two "tech" skills. I'm really, really good at systems analysis, and I'm pretty good at translating user requirements into code more or less on time and more or less with few bugs. Sure the tools and techniques have changed a bit, but much less than some would claim. After you learn your 5th or 6th language the 7th isn't a big deal. I really don't see any deep need to learn new skills beyond those two as long as I stay in the field, after all, its worked very well so far... Eventually due to ageism I'll have to do "something" else. Maybe learn the skill of management, or sales, or something like that. Donno. What does a good techie do when no one will hire him for non-tech related reasons? Maybe start a tech company, thus the interest in HN...
On resumes the "no new skills" crowd knows you can just make it up in six months if you want. For a software dev who's any good, how long does it take to learn something, contribute to an OSS project, etc? Not very long, thats for sure. New stuff comes along at every job I've ever had, and I have to implement it in a month or so. Not hire a new guy, not go take a class, production code. Its so not a big deal. There's no point in learning a new skill and telling anyone at work about it, unless you think its funny to get escorted out... after all, why update the resume unless you're looking?
The other big mistake is virtually none of the detroit workers had the skill of making cars. There are people who have the skill of making cars. I have a cousin with that skill, who's a large diesel mechanic who has a hobby of tearing down cars and rebuilding, all by himself, bare metal components up, including (obviously?) engine assembly. He's stripped and rebuilt two classic corvettes and a ancient jeep, so far. Virtually no autoworkers can do that other than coincidentally as a hobby. They can tighten a bolt on a line, or align an assembly, or insert/stack partially finished parts, or press a e-stop button if the robot goes nuts. They suffer from HR doing "keyword selection" just as much as we do now. Oh look he worked on a car line, well he is totally unqualified to tighten the same bolt on our truck line. Anyway, none of them can build a car. Once, a long time ago, I worked in IT at a large regional printer. That doesn't mean I was a "press worker" or I could do much of anything with putting ink on paper other than program ethernet switches for embedded control devices. "autoworkers" are the same way.