Sometimes it is necessary to make the shop unaccessible for public.
For example for an holiday, or maintenance, or the page is already used but a new shop should be added.
There are different possibilites.
When the whole page has a security issue for example, it maybe usefull to block the whole page by using the joomla feature.
When you want to work on the store, but public should be excluded use Joomla groups. Just enable the access for the editor group only.
Or when you want to set the shop in holidays mode, use the catalogue function. This is very handy, because all links keep intact for search engines.