DMs are just writers that have an idea for a story, but don't feel like writing a book.

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?