Lolo De Puzlo!

This is a subject of much interest to me!

I find the idea that fiction is for tricking people into agreeing with you to be tiresome and immature, but I also think the difference here is more about the viewpoint of the person involved and how good a writer they are. Worldbuilding is an extremely political craft. The decision to write about the way you think the world is will obviously run into your own beliefs about the way the world is. I don't write to teach anyone any lessons, but I do write for my own personal goals and beliefs. It just happens that my politics are against the people who think 'teaching a lesson' is a meaningful goal in fiction.

Story-telling has an agenda, even if it's just what you choose to include.

Why are you telling us about Rhapsody? Or Sarah? Your world has billions of people in it. You could be sharing stories with us about politicians, criminals, soldiers, scientists, underwater-welders, children, stockbrokers, anchorites, and chandlers. Why did you choose the people you chose? Why are they so important enough that you chose them and not others?

This thesis isn't an accusation of some nefarious plot. You're right that good fiction doesn't feel manipulative. But good fiction is a manipulation.

It would be better to say that, "all stories have a theme". A fiction is an elaborate falsity built around truths in the world we inhabit. The "lesson" metaphor is bad because the theme of the story isn't always about making life better. The classic tragedies of Medea, Hamlet, The Trial, STALKER, et al. are about bad things happening to people outside of their control and how they deal with that, which are compelling stories for their catharsis and their relate-ability.

But you're right that not all stories need to be didactic. Sometimes it's just a bunch of stuff that happens. It's just stuff that someone has a compelling reason to tell us about.