I'm surprised no one has already mentioned this, but this idea has been expressed before in Peter Naur's "Programming as Theory Building" (1985): he argues that a program can’t be reduced to its source text; it’s a theory shared by the programmers. When the original team is gone, maintainers must rebuild that theory (often painfully) from the remaining traces.
https://pages.cs.wisc.edu/~remzi/Naur.pdf
Not to say the article doesn't have value, as great foundational ideas are always worth repeating and revisiting.