thanks again. I added a note to the 5.0 docs.
It is certainly fine to still create application-level On Demand processes. However, if a process is related to a single page only, it is immediately clear that the process is part of this page's interface. This is good from a maintenance point of view, because if you only use app-level processes, it can be harder to determine whether the process is still in use and where it is called from.