From my point of view, it is very abstract. So there is a navigation back stack of e.g. screens. Each screen has its own scope. Normally screens are created when pushed to the back stack. And destroyed when popped. But there is a possible use case: the back stack can be recreated, for whatever reason. You may want to retain some objects over such recreations, e.g. a view model. Possible scenarios: system locale change, system theme change, display scale factor, etc.. Anyway, Compose Desktop is multiplatform. So unless recreation is a thing at least in Android, it would be good to have this in common.