Is this actually a problem for society as a whole? Surely a lot of such people would be valuable in industry.
Where? Fintech?
Sorry Sarcasm aside: considering the never ending list of unsolved problems, it should. Sadly, more money seems to get spend on games, ads and stupid juice presses than anything really helpful.
I think it is in a way, since postdocs are often bad preparation for industry. Postdocs usually learn skills that are useful in academia, not the skills that are useful in industry. And the knowledge they focus on is often hyperspecialised, and not necessarily valuable in industry (though that does vary by field).
Essentially, postdocs can be a good way to waste the most valuable years of highly intelligent people...