counterpoint: JSDoc is not typescript

If you define a type in a file with @typedef, it is automatically exported and there is nothing you can do to control that: https://github.com/microsoft/TypeScript/issues/46011

I tried making a library this way and lacking control over the visibility of the exported types was really painful; it made my intellisense awful because every type I defined at the root was exported from the library

I really like it for web components. Lately I have many "my-component.js" files and it's quite nice to just be able to copy them to new projects and have it all work without a build step. But I'm not sure I would use JSDoc over typescript syntax in a large project.

That's technically a fair complaint but feels like a minor nitpick. Just don't `@import` the types you don't want to use.