Earlier quoted context omitted.
I write all of my openapi specs by hand. It's not hard.
I imagine you are very much in the minority. A simple hello world is like a screen full of yaml. The equivalent in graphql (or typespec which I always wanted to try as an authoring format for openapi https://typespec.io/ ) would be a few lines
There is the part where dealing with another tool isn't much worth it most of the time, and the other side where we're already reading/writing screens of yaml or yaml like docs all the time.
Taking time to properly think about and define an entry point is reasonable enough.