These are great observations (from one of your readers and from you).

A journey on the part of the protagonist will only make sense to the audience if the audience experiences a similar journey.

In this particular situation, the audience almost always starts from a state of disunity (otherwise, why would they choose to experience a film?).

The experience of watching the film provides them with a sense of disunity morphing into unity (which is externalized in the protagonist's journey).

If the audience of a film (or a script) doesn't experience their own shift from disunity-to-unity, they won't find the viewing (reading) of the story as satisfactory.