I'm not talking about using sand in the coop/run -- I think that has a LOT of disadvantages and no advantage that I can see. I use deep bedding/deep litter.
I'm talking about my ground -- the area is known as the Sandhills for a very good reason. Back in the Miocene this was prime beach so the ground is mostly fine-grained quartz sand with a few layers of clay here and there.
My younger kids don't know what mud is and had to be taking on vacation into the mountains to see actual rocks that weren't brought in by a landscaper.
Awful for gardening, but perfect for feather-footed chickesn.