Story Structure is not a one-size fits all idea. It has been around since Aristotle, when one of the earliest records of three act structure was suggested, but many variants have been suggested since then, from two / three / four act structures to specific formats like Hero’s Journey and many more.
It is created as a way for writers to organise their stories, but there is a large debate amongst the plotters or pantsers whether structure helps or hinders the creative process. Many writers will of course say that it is more fun and freeing to be a pantser because it allows creative freedom, but even improvisers (many which I have personally met and worked with) point out that they only know how to do that well in the first place because they understand the storytelling theory until they can skilfully execute them at their own leisure without losing control of their own creations.
Given that a lot of successful story franchises follow forms of plot structure very closely and yet still contain creatively different ideas and character choices, I side with plotting over pantsing. Storytelling theory gives a nervous writer with a blank page some sort of direction, a map where to put their big emotional moments so that a story keeps pace and keeps its audience interested. There is no way to pin down every tiny note and guarantee a good story, but it provides building blocks so that rewrites aren’t forced to tackle large chunks of messy unfocused writing; some movies have been scrapped entirely because starting again would take less time than moving all of the pieces around once a script or manuscript is written.
Also, since movie budgets are basically financial investments and critics are louder than ever, they risk sabotaging their own stories if they give too much funding to a story that is not up to standard. They must be extra selective about who they sign on, which projects they agree to fund, and ensure that their money is made back lest their next production be forced to function on a much more difficult-to-use budget. Due to the heavy industry pressure around movies, the risk of a story not being picked up or even noticed is enhanced by the slightest dragging of the plot when most of the competition know how to keep their plot flowing from beginning to end without a single major bump or drag. Story structure encourages both companies and art form to keep to a high standard for the sake of their audience.
Storytelling is about giving your audience the best experience, and marketing is about pleasing your audience, so it only makes sense that story structure has risen in other areas. Video games used to be down to a sequence of tasks, but cut scenes have become regular since games have been offering complete story arcs to enhance the experience – to the point where they now obtain rights from movies and not only make a game around the franchise but create the stories within those movies (i.e. the Lego video games). Even the Aami ads use characters like Ronda and Katut to sell a romance story rather than the product, with each ad structured like a mini-episode; same with the Barbara From Bank World ads selling a relatable-yet-exaggerated sequence of bad bank experiences to entertain its bank customers.
What is becoming clear over time is that the product or concept alone is not enough – in fact if the product is good and the structure is poor, there is often a decline in the enjoyment of that product. Story structure is the spine behind the entire product; it holds it up and elevates the creative opportunities while still keeping focus.