Why did the author include a description about the theories behind Earhart's disappearance?

The author included a description of the theories behind Earhart's disappearance to provide a wider analysis of the context and play with the reader's mind.

Explanation:

First of all, this is a very common element that psychological writers use to play tricks in the mind of readers. It provides different perspectives on the occurrence and outcome of the event in the matter to open the perspective of the reader and make him hook, think, and elaborate his judgments about the mystery in the story.