What's the point of Item Exchange event?

I noticed the event "Item Exchange" which is available via the Festive Balloon:

In this "event" we can replace items (stones in that case) with items that when used, provide those same exact items again.

I gave it a try, and there's no bonus or additional items while doing that.

What is the point of this event? Why would anyone want chests instead of the stones?

This is for high spending players who have bought so many items that it would go over the 9999 item stack limit. Instead of increasing the limit, IGG have decided to do this to allow people to have more items in their warehouse. Whenever they actually want to use the items they use these chests to get the items out.