Just to clarify, I'm suggesting this for both the reasons of QOL and immersion. The feature would be nice to have, there's a lot of room for adjusting the difficulty of doing such an activity as commented above AND it'd be far more immersive than having to open up a third party image upload site mid session.
Also, it could end up creating a role within groups of a cartographer, I think it's safe to assume that coordinated groups of survivors would have their "map guy" taking care of everything map related.