During a pitch on open moorland in the UK we used nuts to set up our hammocks between a large boulder and a series of boulders further upslope. The nuts where inserted into some cracks behind the boulder saving the use of a lot of rope or tape. Without them we would have had try and put slings around large slippery boulders.
We have planned two more trips in the future to areas where there are no trees and will need climbing nuts and slings to set up. Why? well it's fun and comfortable to use a hammock in these places!