Stories serve the purpose of consolidating whatever gains people or their leaders have made or imagine they have made in their existing journey thorough the world.
Each of my books is different. Deliberately... I wanted to create my society, my people, in their fullness.
Once a novel gets going and I know it is viable, I don't then worry about plot or themes. These things will come in almost automatically because the characters are now pulling the story.
Many writers can't make a living. So to be able to teach how to write is valuable to them. But I don't really know about its value to the student. I don't mean it's useless. But I wouldn't have wanted anyone to teach me how to write.