We were comparing the amount of time it takes to write a textbook versus the amount of time it takes to write all the papers the textbook cites (or relies on, I guess). So I don't think "hardness" and the fact that papers also cite other papers really changes this comparison.
I mean, a textbook might take years to write/edit (on and off) But it takes at least a month (on and off) to write/edit a paper.
But you don't think this is a learnable thing? Doing a paper, you already have to write code. Just structure it differently.
As it is, the code is often neglected. And rarely shared. Both bad facets.
And making a full text book that is executable is what I was comparing. That entire book is a program. I'd imagine that was much harder than the typical paper. Many of which are surveys and gloss over deficiency of the supporting code. (Again, I still concede the black swan nature of that book.)
I mean, a textbook might take years to write/edit (on and off) But it takes at least a month (on and off) to write/edit a paper.