It should be a statement of fact, but it took Hollywood, or more generally the American animation industry a long time to get to that realization. For the longest time, writers had to struggle to put any kind of complexity into their shows, animation was generally run to the lowest (cheapest) common denominator and story arcs were more or less unheard of.
Trust me, if you lived through the 1960s, 1970s, and early 1980s you know what I’m talking about. There were some bright points, but for the most part, complexity in storytelling was something that wasn’t prized, and what you got was often due to writers and artists pushing back against what they were being told to do.
How different things are today! Gravity Falls, Trollhunters, Jurassic Park, Camp Cretaceous... All of these and more are examples of shows with long, complex story arcs that run from episode to episode, and from season to season. The idea of shows made up of nothing but stand alone episodes, with no attempt to craft a larger narrative has become increasingly endangered, and the general assumption is that children can keep track of these complex stories, and will enjoy keeping track of them.
Even My Little Pony, which, despite it’s appeal to older viewers, is primarily targeted at a younger age, created a coherent and developing story over the course of its run.
There are a lot of reasons for this, some of which I’ll talk about in later articles, but for now, just consider that increasingly, animation is now treated as, and seen as a legitimate, serious artform by both children and adults.
We’ve come a long way since the 1970s.