In Portal 2, when I no clip through the world, I sometimes notice these unreachable boxes, and different shapes floating in the middle of nowhere.
This map was made by valve, and you can see these boxes on almost every single map
From experience with the Portal 2 Authoring tools, I know that no props, objects, functions can exist in the void, and have to be sealed in walls, or you get a "leak". This is said to be because the game engine needs to separate the void from the playable area.
Is there any actual benefit to putting logic outside of the map, as having it inside does not interfere with playability at all? If I was to make a map, why would putting logic outside benefit me in any way?