Why can digressions be effective in essays and travel writing?

In the context of nonfictional prose, digressions are considered an artful technique that enhances the reader's experience by providing relief from the intense, persistent focus required by an author’s primary argument or purpose.1

In essays and travel sketches, these departures—which function as asides, tangents, or excursions—offer a pleasant contrast to the rigid structures often found in modern fiction. By allowing the author’s "meandering fancy" to take hold, digressions create an impression of freedom and authenticity that feels closer to the unpredictable nature of real life. This stylistic choice enables writers to blend facts with dreams, incorporate the illogical, and introduce delightful eccentricities, ultimately providing a sense of spontaneity that is often unattainable in more strictly logical or carefully wrought narrative forms.231