Imagine a printing frame that is not oriented uprightly.
That's not really answering the question.
It's a bit like somebody saying "I want a hollowed out space in my automobile's seats so I can sit in the automobile wearing a parachute." And then, when you ask, "What's the scenario for wearing a parachute in your car?" ... the reply is, "Well, when the car flies I want to be able to parachute out of it in case of trouble." OK. Not really applicable since automobiles don't fly.
In this case, layouts and maps in Manifold are North Up. They don't rotate either in map views or in layouts. So, sure, you can image a printing frame that is not oriented upright, but that's not a scenario in Manifold.
For now, I'm curious what the scenario is today for rotating labels. I respect the original poster for asking about them, and curious what the scenario is today for using them.
PS: If what is desired is generalized rotation of map views and frames without layouts, that's a fine thing to discuss. There are very many details involved in such things so if anybody wants to prioritize such new capabilities it would be a great idea to launch a thread to discuss them to sort out issues before sending in a Suggestion. For example, most web servers don't rotate views other than North Up. How do you want to handle those, given the immense popularity of web servers as background maps? But that's worth a thread of its own, not cheating the importance of the topic by discussing it en passant in a different thread.