That makes more sense. Still, I think the point stands; tracking different things is different enough that trying to fit all of them into the same framework wouldn't be ideal. Off the top of my head, one example is how a 'watched'/'read' list is needed for books and movies, but a 'listened to' list wouldn't make a lot of sense for music; while on the other hand an 'owned' list is important for music, but not as relevant for books and movies. There's plenty that would make sense to federate of course, like reviews, but if it was me making this I would be much more inclined to have separate backends with certain parts having ActivityPub integration.