Epics can include Epics/Issues across top-level Groups
Problem to solve
Some installs of GitLab (mostly on-prem?) were set up such that the top level groups match the organization's structure. In our case, we upgraded to GitLab EE from Core, but now epics aren't as useful as they could be because epics can't include epics or issues that exist in other top level groups.
Intended users
Product managers and team leads coordinating projects across teams/groups/departments.
Further details
Universities may find this especially helpful where a Computer Science department might rarely collaborate with the Library (both using an instance of GitLab maintained by a central IT organization) so they have their own top level organizations, but they later find themselves looking to collaborate on a larger project (that might involve existing code repositories).
Permissions and Security
Permissions may complicate things, and will certainly require discussion. Anyone with read access to an Epic in organization A could inherently read associated issues and epics from Organization B.
Perhaps only users with maintainer or higher in both organizations should be able to link epics/issues across issues (and never confidential issues).
What is the type of buyer?
Anyone using epics, especially those upgrading from core would find a feature like this to make adoption easier.