Maybe, I don't know.
I do know people with old disks in the house that keep thinking they can re-use them someday. Often they are old USB disks.
I suspect those are the disks they'd be adding to a pool "in emergencies", that is when all at the sudden they realize they need few extra MB for whatever they're downloading in that very moment.

Interestingly, you may add SD or CF memory cards to a pool! I like that you can, but I am a bit uncomfortable thinking of the possible misusage...