You would still need a subscription for the data. The integration into MSFS is not what you are paying for. I have been using Navigraph for years and their integration into various products is a service and entirely up to the developer. Just because an aircraft (as an example) has built in support for Navigraph data does not mean you get the data. (Although the developer will often supply an out of date AIRAC along with the aircraft).
The changes in the XML is simply to tell MSFS what data to use.