Thanks so much for this opportunity.
It would be so, so nice if user-assigned state could be easily associated with entities. Right now, a helper is needed, and while that is a viable way to keep track of user-assigned state, it is a maintenance hazard that requires configuring a helper for each new entity that needs user-assigned state.
I am not sure about the implementation, but it should be fairly easy to just add and/or remove dictionary entries to a special user-assigned state attribute of an entity. It would streamline advanced automations so much.
If I’m hitting a paradigm clash here where HA has a preferred way to do this that doesn’t require maintaining helpers separate of entities such as lights and sensors, or this suggestion reduces to an absurdity when considered in view of how it would actually work, I am happy to be defeated on this suggestion.