It might be that modern readers have other things they can read/do with their time. In pre internet times it wasn't so much the case - you'd buy a mag or book and then read it but now there are many alternatives a click away.

Pros and cons but often in the old days it was spun out to fill some volume the the printing press was set for like 400 pages in a book. I did Great Expectations at school which had about ten chapters with the main story and then about 60 chapters of irrelevant stuff because Dickens was paid weekly by the chapter.