Why is it useful?
This is useful for Digital Teams who manage a cluster (clones) of the same basic site and who do not want to have to do every tiny change themselves, but allow the editors a certain amount of freedom to add defined widgets or sections.
Generally the central team provides a master site but the country editor(s) have some ability to make small changes or even do basic page changes.
Think Apple or Microsoft country sites. They are based on one corporate master site but cloned and localized - a bit here and there is changed, a page or two is different, some sections are removed for products that do not apply in some countries, but otherwise each country site is mostly the same, just in a different language.
Who would benefit?
This is good for digital teams running sites and editors who use sites created by those managers. Especially good for managing multiple websites. It gives a country site editor the limited ability to not only edit content (already possible in web-flow) but to add / delete components that are used to create pages without the complexity.
How would it work?
Something like allowing editors to: