The article touches on a few of the factors, but there are more.
I originally qualified for the PhD program in computer science, and I enjoy teaching, but I ended up going to a master's program. My brother-in-law did go for a PhD in his chosen field.
The options for teaching are (or were when I looked) limited and relatively low pay. I earn 3x the salary with a masters degree in industry. Even with that, universities have reached out to me to teach as an adjunct faculty. For my BIL, he is constantly looking for grants and funding, especially federal funding, which has just vanished. He has said that the biggest block of his time is trying to get funding, the rest is teaching, and he has almost no time for actual research, the reason he went for the PhD in the first place.
I've had schools reach out to me to be an adjunct faculty. I did it for a semester for a class, which was fun for me and I loved the students and got great reviews from them, then realized the problem with it and have sworn it off and warned others away as much as possible. Two decades ago my department only had one adjunct faculty member, someone who had been teaching on the side for over a decade but wanted to primarily stay in industry. These days about 70% of faculty are adjuncts, contract workers with no benefits, with much lower pay than regular professors, and no tenure track for anybody. Like so many businesses, most universities have chosen a race-to-the-bottom for the cheapest workers possible. That means fewer regular jobs for the PhD holders, and if they do manage to get one of the roughly 30% of the remaining jobs, they pay less -- if they pay at all. Many universities have shifted entirely to require some faculty to get their own funding through research grants to justify their pay. Tenure tracks have all but vanished.
And then there's the pay issue again. In my field I can get almost 3x the money working in industry. My BIL doesn't have industry options as an astrophysicist researcher, which is why his time is almost entirely devoted to the search for more money and teaching rather than productive research, which he would much rather be doing.