Why did #ActivityPub create special behaviors such as Like, Announce and Block (and the Undo variants) instead of using Add to or Remove from the associated Collection objects? I have a similar question for outbox and inbox POST, which is an implicit Add to those collections. thaenkin When adding support for extended collections, is an new collection-specific Activity preferred over Add/Remove? FWIW, I see Mastodon uses Add/Remove for pinned and featured posts.