I can see some of the benefits of the integration: emacs can do the horizontal search for TODO entries, create an agenda, let you edit it, and move the changes to the right .org file. Still, I'd argue that the file is the important thing here, not the tool to manage it. I should be able to edit .org files with any other tool (e.g. an android app that eventually modifies a .org file in github), and then do re-process the file.

Other languages also allow exporting to other formats. I use md-to-pdf all the time, and it works well. Integrating the use of other tools in the export process should be independent of the usage of emacs.

There is lots of functionality you can't do without some kind of non-ordinary editor functionality. The table functionality comes to mind, as does the time management functionality. But, really org-mode's syntax is simple and close enough to MD that it's very easy to implement in other editors. There is a vim package and even an Intellij package. But I challenge you to start implementing the non-syntax parts in another editor and you will quickly see that there is a lot of it.

> I should be able to edit .org files [...] and then re-process the file.

You can. It's a plain text file; Emacs provides a "live" and highly interactive UI for it, but nothing prevents you editing elsewhere and invoking Emacs, in "batch" (i.e. UI-less pure language interpreter) mode if you like, to evaluate, export, or perform whatever other actions on the file. I do this all the time, albeit in an interactive Emacs, with Editorial on my phone and files synced in Dropbox.

There are also libraries in languages other than elisp which provide some export functionality; notably, Github uses org-ruby, I think it's called, to HTMLify org files for web UI rendering.

Well, you can edit it in any text editor. You just don't get the automatic formatting, coloring, table calculations and so on that all depend on elisp.

> The synergy with other Emacs packages is enormous.

I've been experimenting toward a modern SQL interaction mode, and an Org buffer makes a brilliant place for output - native handling of tabular data, syntax-highlighted code blocks each with the query that produced a given result, headlines, plenty of place for user-added annotations, built-in export, overall a ton of work that I don't have to do.