OK here's the diagram:

Can anyone explain this to me please?
If I use the red box Add a child issue OR the red box Parent, I'm bound by the Issue Hierarchy. Child issues show up in the red box Child issues area, and the breadcrumb does it's thing (but only the immediate parent, apparently?)
But if I use the green Link Issue button, and I set this Epic as a parent of another Epic, why does it show in the Linked Issues green section with a Parent of descriptor?
If it's a parent, shouldn't the children be altogether?
Please do not lecture me on the finer points of project management and how making Epics parents of Epics shouldn't be a thing. We can debate that in another thread somewhere sometime.