Most books, many catalogs, and any publications that have a table of contents or glossary require page numbering. A standard book is normally divided into chapters that give the reader natural breaks. These can be in the narrative, as in the case of a story such as a novel. Chapters also mark different sections, possibly covering various subjects. Page numbering allows readers to quickly access the relevant sections.
This is particularly useful when the publication is likely to be accessed repeatedly.
A cookbook or academic book would be a good example of this. A reader may only be interested in one section or constantly refer to a certain chapter.
Magazines, newspapers, brochures, and reports are all normally numbered to help the reader.