A friend of mine forwarded me this facetious article about the narrative structure in films, which left me thinking about why exactly a consistent structure like the one that is found in Freytag's Triangle might be found so prevalently.
Studies on "story structure" have consistently found that people (in our culture) have better memory for stories that follow this arc than those that don't, indicating that it isn't just a vogue thing — it's cognitively advantageous. So, on the one hand, we might attribute this to an "innate" universal structure found in people's minds. This would be in contrast to the idea that there is an "archetype" floating out in the world that stories follow. Really, as with most all human behavior, there are no structures "out there" — the only place that such structures can exist is in people's minds.
Of course, the immediate comeback that might arise would be that not all cultures' stories follow this Aristotelian narrative arc. However, a simple fix around this would be that, like the patterns in languages, different cultures might externally have different narrative patterns, but the capacity of all human minds have structures that allow those diverse patterns to emerge.
For example, most all languages use Subjects, Objects, and Verbs, though they put them in differing orders. It may be the case that analogous categories exist for narrative, but that the Aristotelian narrative arc simply is one of the patterns that these categories are put into for a (i.e. our) particular culture.
Deeper though, we should think about the function of narrative in the first place. It seems implicit amongst most approaches that narrative is for telling stories. However, why might a mind have a need to tell "stories" specifically? Rather, I think stories are merely a symptom of the broader function, which would appear to be about ordering information — particularly about objects and events.
With such an organizational system in place, stories serve a cognitive purpose as a way to facilitate comprehension and memory. Entertainment and artistry for those stories is just a affective bonus.