It's a deceptively simple criteria to apply. It's simple because the question is straightforward. It's deceptive because you might expand the definition of joy, lumping possessions under "it used to bring me joy", or "it was a joy to receive it."
I own a lot of things, but not all of them bring me joy. Because I have an unfinished basement, I can afford to keep things simply for nostalgia's sake, or inertia's sake. I can afford to keep all my excess baggage.
My wife and I were inspired by Kondo's ideas though. We began to purge things more frequently since 2014. We know that the joy of possessing something can be short-lived, and nothing is wrong with that.
A fond acquaintance told us "You own possessions, possessions shouldn't own you." As my wife and I perform the magic of tidying up, I remind myself that the most joyful things are things I can't possess: health, relationships, ideas. The rest can be given away.