I think it is funny because, in reality, these different features would not appear in the world right next to one another. This map is a dramatization of geological features with no variation or nuance that naturally occurs. But for video games, it is easier to differentiate areas with these clear geological differences so the player can be like, "Oh yes, the island town." Or "it's close to the mountain" It's just an acknowlegdment if how so many video games have done the same strange thing in order to streamline gameplay.