One of the great things about The Practice of Programming is how much it references other non-coding works. You can tell Kernighan draws his knowledge from many sources, not just technical ones.
They invented it and that is also why they are able to express their ideas so clearly. Small groups of smart people at various institutes/companies coming up with ideas, bouncing it off of each other, learning from each other and settling on the essence.
The mathematician Abel is supposed to have said; "It appears to me that if one wishes to make progress in mathematics, one should study the masters and not the pupils." This is true of all domains.
Math(s) background is one guess I can make. Based on the fact that many of those pioneers had a basic degree in math and then pivoted (heh) into computer science. In fact some of them started before computer science was even a formal thing.