Nothing in the article about what one really learns in a Ph.D. program. Here are the things you only learn in a Ph.D. program, more or less in chronological order:
1. What kind of information you will find in each section of a research paper in your field.
2. What are the major research programs in your field and where they disagree.
3. How to identify where a paper's author stands with respect to the major disagreements in your field.
4. How to decide that a paper isn't worth your time without reading all of it.
5. How do you write a research paper?
6. How do you decide what research to do? (This decision will often be made for you for the first couple of years.)
7. Where you stand with respect to the major disagreements in your field.
8. How to synthesize half a decade's work into a realtively brief document.
Notably, these skills don't help you do any of the following:
1. Manage a research group in an academic setting.
2. Teach undergraduates.
3. Manage people in industry.
You might pick up applicable skills along the way, but these are incidental. Any specific skill, any particular knowledge, can be obtained without getting a Ph.D. The Ph.D. teaches what you need to know to advance the field.
I'd like to return for a second to talk about teaching undergraduates. It's a very important thing to do. Ph.D. training ought to include pedagogy. Standards for university instruction are shockingly low, and professors are rarely held to account for failing to teach the material well, especially at R1 institutions. However this comment is not about what you should learn, but about what you'll actually learn in a Ph.D. program if you decide to enroll tomorrow.
I agree with your main point here, but I think you're trying to paint and overly broad claim about PhD programs, which are extremely different between institutions. It's like saying "working at a company is like this... you learn this but not that."
Specifically,
1. Senior PhD students in many research groups can become de facto managers of the group, especially when the professor is on sabbatical. PhD students are often involved in the funding, presentations, recruitment, and represent the group. Some PIs/professors empower their PhD students to run a mini research group within their group.
2. I've seen some PhD programs have a strong emphasis on teaching undergraduates, both as in teaching undergraduate courses directly (which many PhD students in the humanities and social science already do), serving as teaching assistants with a substantive educational role (not just grading), and mentoring them in research or more general advising. For example, Brown University and Princeton are known to have a good research-teaching balance for PhD students. Brown has a large number of programs that help PhD students get more involved in undergraduate teaching [https://www.brown.edu/sheridan/programs-services/certificate...]
1-4 can be learned by anyone willing to read enough papers in a great, great many fields. The math needed to understand the articles in the Quarterly Journal of Economics or the American Political Science review is in most cases well within reach for the population of potential applicants for a doctorate.
There’s an enormous amount of valuable non-procedural knowledge that most doctoral degree holders have and most non-holders don’t but the average doctor, lawyer or senior civil servant does research that would be impossible without skills 1-4 without ever doing a Ph.D.
1. What kind of information you will find in each section of a research paper in your field.
2. What are the major research programs in your field and where they disagree.
3. How to identify where a paper's author stands with respect to the major disagreements in your field.
4. How to decide that a paper isn't worth your time without reading all of it.
5. How do you write a research paper?
6. How do you decide what research to do? (This decision will often be made for you for the first couple of years.)
7. Where you stand with respect to the major disagreements in your field.
8. How to synthesize half a decade's work into a realtively brief document.
Notably, these skills don't help you do any of the following:
1. Manage a research group in an academic setting.
2. Teach undergraduates.
3. Manage people in industry.
You might pick up applicable skills along the way, but these are incidental. Any specific skill, any particular knowledge, can be obtained without getting a Ph.D. The Ph.D. teaches what you need to know to advance the field.
I'd like to return for a second to talk about teaching undergraduates. It's a very important thing to do. Ph.D. training ought to include pedagogy. Standards for university instruction are shockingly low, and professors are rarely held to account for failing to teach the material well, especially at R1 institutions. However this comment is not about what you should learn, but about what you'll actually learn in a Ph.D. program if you decide to enroll tomorrow.