And I wouldn't disagree! But keep in mind the difference between "a PhD" and "a research professor." My points about Academic culture were specifically about the culture of research professors — and of the graduate-degree-program insofar as it exists as a system for at becoming such.

Let me restate my points a different way:

1. The whole University system has always been set up to rely on the existence of independently-wealthy professors. There has been no consideration ever given to surviving on a professor's salary, with or without tenure, as the University-as-institution is not set up to expect professors to need the salary the University pays them. Professors are basically expected to have other jobs — usually upper-class, no-real-work-expected "head of a nonprofit" kind of jobs. They're expected to have these jobs before becoming a professor. A professorship was, historically, just something you would stumble into out of a career as a "man of science" (which is like being a "man of leisure", but with more science.) The pay is a bit like the pay for jury duty: it's a stipend for taking time out of your life to do something that's worthwhile, but not profitable in its own right.

2. In the distant history of the concept of higher education (Ancient Greek through to ~medieval), research professors came first; and at first there was no codified progression system that would make you into one. Rather, Universities were "monasteries of research"; if you would attend them to learn, it would be in the same sense that apprentices attended a master artisan's workshop. The people doing the research there would put you to work (in research), already expecting you to have a grounding in the culture required to understand the work to be done (which you'd get from your parents, and from private tutors, or from being sent to e.g. grammar school.) Over the course of helping out with such research, you'd hopefully attain a useful education in something. The research professors did not give "remedial education" lectures, except insofar as a team lead might give a lecture to their team about how to do the work they're doing. They sometimes gave public lectures about their advances, or debated other professors, but neither of these were with the goal of giving "an education" to the attendees of the University.

3. As with the trades, if you wanted to become part of Academia yourself, there was a "journeyman" phase: you'd graduate from the school you attended, then go off and have a career in the arts or sciences. That career might take you into close collaboration with the staff of a particular University; and that might then naturally lead to you being offered a professorship there. This professorship was always tenured; there was no concept of a non-tenured position. A non-tenured position (with some temporary office space, use of labs, a stipend for lunch from the cafe, etc) is what you already had just by the fact of partnering with the University in your private work!

4. Circa the Renaissance, the "University as higher public education" concept was invented, bringing in the concepts of research professors giving "remedial higher education" lectures; of teaching assistants; of paying to attend the school; of the nouveau-riche sending their children to the school to be "raised up" to the upper-class through exposure to the liberal arts; and so forth. This proved to be a successful model for several centuries, although it seems to be falling apart today. (It also closely mirrored the introduction of officer candidate schools in military contexts.)

5. Later, seeing the success of the "higher public education" concept in minting new members of the upper class from middle-class University attendees, there was an attempt to create a similar process that would mint people having the specific culture that academic research itself had: to create researchers from whole cloth, without them needing a career as a journeyman scientist. This led to the creation of the PhD system, the concept of the tenure track, the concept of adjunct professors, the cordoning-off of apprenticeship duties to "graduate" rather than "undergraduate" attendees of the University, the concept of a "teaching assistant" being a "graduate" position, and so forth.

This kind of worked, but when it did, it only worked because the people becoming professors were already members of the upper class. (Note how it's possible to do a doctorate program without first doing any kind of undergrad program, but that this is rarely done. The expectation is that those already in the upper class would just go straight to a doctorate program; while those in the middle class would need enculturation to the upper class first, through an undergraduate program.)

6. Due to the removal of real apprenticeship duties from undergraduate programs, the "spirit" that made undergraduate programs real engines of enculturation began to fall out. If an undergraduate higher-education program was just a bunch of lectures and homework, then anyone could run one; and so Universities began popping up all over that offered the same undergraduate education but didn't do any enculturating.

This also meant that "having a University undergraduate education" could no longer be used as a signal that someone would be able to successfully take part in a PhD programs. So the oldest Universities became picky and whitelist-bound — the creation of the Ivy League as a useful concept (separate from a sporting context) is due to their recognizing only undergrad degrees from certain "sibling" Universities as being worth something (that something is enculturation!) in graduate-program intake.

But all the other, newer universities and colleges and technical institutes? They just blindly went on trying to make graduate degrees and tenure tracks work, cargo-culting the process invented (and then discovered to only work given specific prerequisites) by the old Universities. (Hey, cargo-culting their undergrad degrees worked, so why shouldn't cargo-culting their graduate programs?)

So most universities proceed without a clear understanding of the fact that Harvard and Yale have the pay scales for grad-students and tenure-track professors that they do, because the people staffing those positions are of a certain socioeconomic standing, that is unique to Harvard and Yale. They copy the pay scales, but they can't copy the candidate pool. So instead, they force middle-class people to try to survive on pay that exists — as part of a system designed centuries ago — to serve as an upper-class "trivial stipend." And then people wonder why nobody wants to work in academia.