Yes that's the idea. Avoid having to write an Activity just for orchestrating the save of an instance.
It also provides a level of abstraction between the Application and the source of the data. Now that Data Pages can both load and save data, the Application is insulated from changes in how or where the data is saved.
For example, a Customer Service interaction may retrieve a Customer, update some personal details and need to ensure those changes are saved. The Savable Data Page allows the Application to simply say "Save this instance now". The logic about writing to a database; making a REST call; running a robot, or some combination of these is encapsulated in the Data Page which can be independently Unit Tested. This makes reusability of this class of data better as the Data Pages provide clear APIs to the Application for both read and write.