Would be very useful for Bootstrap menu drop-downs, where typically The hovered element (parent) is not it self a link, it just serves to open sub-menu with actual links.
I believe there are a few options for this.
Both options allow you to create pages that would be in the sitemap, which allows you to nest pages and more easily manage them.
Manual Nav is a very useful add-on, the only limitation is that it provides one "level" for navigation. It does not create nested navigation, for example levels for a drop-down.