But you don't want to do reporting on an application's data model, that doesn't scale: as soon as you have a medium-sized business, the data will not be confine

But you don't want to do reporting on an application's data model, that doesn't scale: as soon as you have a medium-sized business, the data will not be confined to a single application (unless that application is named SAP). Understanding the business data model is a requirement for SQL analysts anyway, and once you have the application data transformed to the business model, the business users will have no trouble understanding it.