That is correct. XMOD is the engine under this application. Without it, this application will not run.
That said once you have xmod there are many other applications you can build or have built to fit your needs without having to be a full on developer.
For example, I have built House listings with detailed floor plans, simple store fronts, links modules, helpdesk type ticketing systems, class schedule listing with ability to signs up for the class, etc....
Hope this helps.