I'm not sure Kenrou because there are more than a few such single player map mods (aka. locations) in Fallout 4. You could have an NPC in your location that wouldn't affect the rest of the game because your map/location would be entirely separate from the main game except for the loot, experience, weapons, armor you can collect there. I'm sure there are locations in plain-jane Fallout 4 that don't affect the rest of the game (quests, NPCs) except in the sense of giving you experience, loot, weapons, armor. IOW there are locations you don't even have to visit to complete the game storyline (which was also true in Fallout 3).
The DLCs for Fallout 4 are such new locations. You can complete the main storyline of the game without ever playing the DLCs or even having them.