Back then, i think full professors were appointed by the Queen. (Certainly so for Beatrix, but he became a prof before her inauguration)
Being appointed by the Queen made it really difficult to fire you - one of the reasons (I was told) they stopped this practice.
Moreover, back then research funding worked very different from how it works now in .nl. Actually, I have some idea of how finding worked from the mid-90s on... but I've read that prior to early 80s, in .nl, most PhD students were part-time and not employed by the university.
Not sure how accurate that is. Irrespective of its accuracy, it's clear that academic life had changed drastically since then. (In .nl at least)
Monarchies today being at that awkward stage where they wield enough protection to prevent somebody from being fired but no longer enough power to get them beheaded…
*Tuesday Afternoon Club [0].
[0] https://www.cwi.nl/about/history/e-w-dijkstra-brilliant-colo...
According to the article, as a young researcher, he was
* A "programmer" (something like a research assistant, perhaps?) at the Mathematisch Centrum (Mathematical Centre) in Amsterdam.
* Professor in the mathematics department of the Eindhoven University of Technology from 1962-1973. (As I understand, the "external funding" thing is less of a problem in mathematics. Also, I have no idea how tenure works there.)
* Finally, research fellow at the Burroughs Corporation.
It's true, he didn't have many direct PhD students (two?!), but his collaborations were many. (I don't know if the Tuesday Morning Group at UT is still active,[1] but it was rather well known and its members produced a great deal of what is now "theoretical computer science".)
If you're trying to compare Dijkstra to J. Random Young Researcher, J's gonna have a hard time any way you look at it.
[1] UT no longer requires automata theory or formal logic for CS undergraduates. They're dead to me.