Kind of a shower thought, and maybe it’s just how I run campaigns, but it feels like there’s a lot of parallels between DMing and that guy who has a great idea for a book/movie but will never write a single page.
The DM comes up with “So what if there’s this guy with this magic power, and the only way to beat him is through a very specific process.” And then all the Players decide: who are the characters? What do they do? What do they say? How’s it all work out?
The campaigns my players consistently voice as their favorites are ones where I created an overarching plot, and then incorporated their backstories as significant and impactful portions of that plot. Being the sole input for character motivations for a story (as with a book) makes it easier to end up with a coherent vision and story, but more difficult because of the amount of content you’re responsible for. Conversely a good DM can offload work to players and end up with a result that everyone is personally invested in.
I will say though that some DMs end up writing thousands of pages over the course of years spent in an ongoing campaign and might cry at your characterization.
It’s definitely POSSIBLE to run a campaign without ever writing a page, but good luck when your characters get attached to an NPC you forgot about if improvisation isn’t your forte.