Although the linked article was refreshingly readable, the general answer to your question is because more text = more opportunity to weave adverts in between t

Although the linked article was refreshingly readable, the general answer to your question is because more text = more opportunity to weave adverts in between the paragraphs. Storytelling is an easy way to bulk out the text when your facts are light. Also, to be less cynical, some people are after entertainment as much as education, and will enjoy reading a story rather than a lecture.