Because variables & values are stored in save game files, which means that, that information will have been reset to its initial state on game launch, until you restore the data by loading a save file.
Writing & reading data to / from an external files does not rely on save game data, which is why you can have the game restore option settings & retrieve other data on game launch such as achievements, bonus unlocks, date / time, player profile names & so on.
Please see:
here &
here, for more information regarding the config.ini & reading / writing of external files.