So it's not an example of 'the paper selling the book'...
In my experience, it's unusual for a book (besides textbooks) to contain more scientific information than the papers it's based on. They're usually concerned with background information, explanations of relevance, implications, and consequences.
But, whatever.
Not quite causal but true nonetheless.
The kind of people I used to follow were such as Athans and Falb In optimal control and estimation. The papers were interesting but very much each was a narrow monograph.
The papers made me buy the book.
The range of examples in the book did extend papers more towards what interested me.
Maths subjects are like that. What is your professional subject area?
In the subject that inspired my comment, it is fair comment.
The shroud.
Rogers put far more detail in the book than the paper. Reading the paper made me want the book published later.
Ditto Fanti puts all the working data in a book - eg dating by physio chemical properties , which is much more detailed than his paper.
So did antonacii, Marino and meacham. To name but a few, the papers only scratched a surface. The book supplied detail.
I wish the radio daters had done what Fanti did with his working data.
Then it wouldn’t have taken 20 years to expose how the nature article cheated the consistency tests - but also raw data ( only got by FOI) proved the samples had radio date sequence and were not consistent in a sequenced way. So not reliable. So books with raw data - as fantis did help.
Your phrase “They're usually concerned with background information, explanations of relevance, implications, and consequences.”
That Is more scientific information in my opinion.
So that’s why we may be disputing it.
I suspect you mean doesn’t break new ground.