The introductions to some books are full of acknowledgements and thanks to those played a key role in the books. Introductions to genealogical publications, particularly transcriptions of original documents, may mention how the records were accessed, the condition of those records, what records were missing, etc.
Those are details someone using the book needs to know. When using any published transcriptions of original records, read the introduction, preface, etc. There may things in there a researcher needs to know to use the publication effectively.
I’ve been reading Fields, Fens and Felonies: Crime and Justice in Eighteenth-Century East Anglia–the author discusses his process in the introduction. That was an education in itself.