Well, I just meant for speaking at MI. The Institute says so much about college being wasteful, the misdirection of education, and so on, it would be ironic if this were a formal requirement for faculty.
Now, what you say is generally true, but not always. Saul Kripke comes to mind, as does Tony Martin, both tenured full professors at excellent universities (Oxford and Berkeley, I believe). In essence, with a PhD and mediocre “discoveries” one can succeed, but without a PhD it takes remarkable research. It’s a middle path vs. extremes thing. For the vast majority of us, a PhD is the only way, but for the genius (who really belongs there) it isn’t. That said, I generally agree with everything you’ve pointed out.
However, I do disagree on the ‘rigor of a classical education.’ I agree in principle, but where is this classical education offered anymore? Colleges lost that focus decades ago, and indeed, even those critical of the current system point to things like “the teaching is irrelevant to employment” thereby asking for less classical education, not more. Furthermore, in talking about the PhD in particular, in my graduate experience the classroom stuff was by far the least of it. There were required courses, but they were not the major part of the training, nor did they particularly develop depth of understanding. In my experience, depth of understanding came from the weeks getting ready for the prelims. To answer the questions on those tests required depth and connectedness of knowledge. Many schools post their prelim questions online, and you can print them out and spend the time I spent, and you’ll have that. The rest of the degree, which also developed that ability, was voluminous research and reading - which you can do without being in a formal PhD program. Debating is a very particular aspect of scholarship, and yes, Krugman would have eaten you alive, particularly assuming he knew your background. If I were debating someone who is self-taught, and I had a PhD in the field, I’d certainly know how to wipe the floor with them. This proves nothing about their understanding of knowledge, just the ‘tricks of the trade.’
On your last paragraph, keep in mind that she’s an an-cap. With a PhD, there will not be any attendant respect of the media. There will be a struggle to get tenure anywhere. There will be attacks on her research. The academic life isn’t for everyone. It wasn’t for me.
I also wonder if unconsciously, we can be trapped by certain irrelevant factors. If she were uglier, I suspect I’d think she had read a lot and was spitting it back.