Why use `root-blank` instead of creating a new subvolume?

[musjj]

Instead of doing this:

nix-config/hosts/common/optional/ephemeral-btrfs.nix

Lines 21 to 24 in 1ad004a

	echo "Cleaning root subvolume"
	btrfs subvolume delete -R "$MNTPOINT/root"
	echo "Restoring blank subvolume"
	btrfs subvolume snapshot "$MNTPOINT/root-blank" "$MNTPOINT/root"

Why not just re-create the root subvolume like this:

echo "Cleaning root subvolume" 
btrfs subvolume delete -R "$MNTPOINT/root" 
echo "Restoring blank subvolume" 
btrfs subvolume create "$MNTPOINT/root"

Is there any reason for keeping a blank snapshot?