I'm not sure holding pattern is fair either. I think doing a postdoc is a normal healthy part of a research career. I don't think most people are ready to start their own groups straight after finishing a PhD.
Which is the entire point getting a PhD in the first place. More research. Forever.
I (along with many others) cringed at the phrasing of postdoctoral degree. A post-doc is not a degree. The article's comparison of a post-doc to law school for liberal arts majors was equally egregious. Sloppy writing.
Now, to be fair to their point. What they are observing is a cultural phenomenon in academia which is to stay in academia until you can't stay any more. Industry is for those who fail at academic research, whether that failure occurs at the post-doc stage or pre-tenure stage. This is in contrast to the sentiments of the real world (the perspective of the article author) which wonders why these "students" take so long to get a real job.
There were fields where post-doc experience was rare:
1. Engineering and computer science, where people had good employment prospects outside of academia
2. The humanities and social sciences, where there was no money to hire post-docs
Fields where post-doc experience was a requirement:
1. The sciences, with an abundance of money for hiring post-docs, and hit-or-miss employment prospects in industry, depending on your specialty and ancillary skills.
The other thing I've observed is that multiple post doc appointments don't really improve your chances. The superstars have identified themselves as such while still in grad school, or during their first post-doc appointment.
I concluded while still in grad school, that the arc of my career would not intersect with a professorship, so I finished my PhD and bailed out of academia.