Here are two examples: I write a blog in org-mode and publish it to html. This is a built in feature of org mode but to configure it I have some emacs lisp code that handles the configuration. Because that code includes functions to generate output paths and so on it would not translate directly to Neovim. You'd have to rewrite the config in lua. Another example is calculated tables. You can manage tables in org-mode but you can also include emacs lisp code to calculate values based on other cells like a spreadsheet. Again these would need an emacs lisp interpreter and all of the context.