It could have had a plug. I think it would be a PITA putting a broom up in there every time you used it. Good idea that never took off.
Back when I was still drinking soda I always wished I had a tube built in to the basement for aluminum cans to drop in a barrel. That was another good idea I never got around to.
The new kitchen wall I’m converting into storage using the double stud bay I left the one bay that has the piping to the upstairs bath open and will fit it with a door. She said do we really need to get to those pipes ever and I said no but it’s the perfect spot to keep the broom. She liked the idea.