Anchor Chain on the Mooring Ball

[SV_Harbinger]

So here is something I saw today bringing my groceries back in the dinghy, it was a boat Looked to be about a high 20s foot sail boat attached to the mooring ball via a chain, about a boat length long and a short snubber, similar to but smaller than what would be used for regular anchoring(I would have taken a picture or two, but the weather isn't the best today and my grocery run is long)
It just struck me as a bit of an odd way of doing it, and was wondering if anyone here has seen similar and if so where? Or of course just what you think of making fast to a mooring ball like that.