It means that:
*If you do not have any modding experience: It will be easier to begin.
*For more advanced modding: You still will need to know a lot of hoi4 specific text editing and formats of different textures/pictures etc.
What we want by doing this is to try and lower the threshold for start modding the game, just as in a OS you will have better and more control by editing everything in external editors specific for that fileformat.
But if you do not need the "full" control or just want to get started without the need to know everything at once, we provide this alternative.