TBH i think a more likely explanation is that they needed to somehow identify separate instances of that data structure and they thought to store some ID or something in it so that when they encountered it next they'd be able to do that without keeping copies of all the data in it and then comparing their data with the system's.

Or you desperately need to tag some system object and the system provides no legitimate means to do so. That can be invaluable when troubleshooting things, or even just understanding how things work when the system fails to document behavior or unreasonably conceals things.

I've been there and done it, and I offer no apologies. The platform preferred and the requirements demanded by The Powers That Be were not my fault.