@eyeinthesky my assumption for why there's multiple methods for achieving relatively similar results is that first the social vocabulary was created as a way to express the actions that the existing platforms already had enshrined, and then other operations, like collection management, were needed.

But as @thisismissemEmelia 👸🏻 already said, the canonical social activities have specific side effects attached to their behaviour that extend to the entire social graph, and those are what ActivityPub actually codifies into its specification.