People use this option so others don't know their secrets... like when they put a furry as the image for the music.

Hiding deck source is useful for stuff you dont want people to know, like stuff you can do with the cli.

anti dwellers are appearing

Deck source, reactions, comments and whole deck hidden by creator

I usually hide deck source because i want the player to explore the deck if its a game and not just look in the deck source to locate something