Why is it useful for historians to craft historical narratives

Contrary to the way most people think of it, history doesn't move linearly. There simply isn't one line of progression that we can follow in order to understand the changes of different civilizations as cause-and-effect relationships. History moves cyclically, backwards and sideways. We're just that complex. You always have to take context into account. Societies and cultures change according to their specific context.

The problem this generates for historians is that it becomes too difficult to explain the evolution of history if the concept of evolution itself is questionable, and every change in society and culture is dependant on their very specific context.

Historians fall into the trap of crafting historical narratives because it's easier for us to understand history by following a linear progression, which of course in reality doesn't exist.

Hope this helps!