Unsurprising. It's the natural byproduct of overproduction of scientists, brutally competitive job markets, and the shortsighted decisions to use publications as the primary metric for hiring and promotion decisions.
Anyone who is alarmed by this hasn't been paying attention to the perverse incentives scientists have been facing for decades.
Any advice for PhD dropouts? I spent years and years pushing against that boundary in an obscure corner of my field and it never moved. What little funding I had dried up and I left grad school with a half finished dissertation, no PhD, and giant pile of broken dreams.
I'm sure over the years you've known students who have started a PhD and not finished. What (if anything) have you said to them? Do you feel their efforts had any value?
In the US at least, it is entirely possible to teach at a university without a PhD. Community colleges are full of instructors with masters's degrees, and tons of classes offered by major universities are taught by graduate students or adjunct faculty without doctorates.
Your job title probably won't be 'professor', but you'll be doing basically the same work as one.
I think this result is obvious to anyone who has spent any time in the academic world, although it is nice to see some solid numbers behind it.
The harsh truth is that key to academic career advancement is who you know much more than what you know. I every single person I knew in graduate school who got a postdoc position did so through informal means (i.e. knowing someone who knew someone), and having letters of recommendation written by the right people from the right departments at the right schools opens all sorts of doors to the academic hierarchy that would otherwise be closed.
Anyone who is alarmed by this hasn't been paying attention to the perverse incentives scientists have been facing for decades.