Extremely few people outside academia are (1) world class at anything, even in a tiny subfield (2) advance the state of the art (3) can explain it in a way clear enough that you can reliably learn something from what they wrote about what they did and how they did it.
That combination describes what a doctoral disserataion is.
The opposite is true in my field, which is half-way between CS and humanities. I've read a few hundred PhD dissertations now and most of them are really not great.
Not a few are more jargon than substance, covering up mediocre ideas with a sugar frosting of math symbols and bizarre wordy academic pseudo-abstraction which obfuscates simple ideas instead of clarifying complex thoughts.
A few are straight out pandering and careerism, with style and content apparently designed to appeal to a specific supervisor.
I was considering a PhD and the quality of the work was the biggest factor that decided me against it.
To be fair it's a fairly niche field. But even so - literally only a handful of those dissertations come close to matching your criteria.
