No, sorry, what I mean is that all users on mastodon.social have a unique private inbox and then a "sharedInbox" value of "https://mastodon.social/inbox". Almost all deliveries (with appropriate "to" and "cc" targeting values that the receiving server can appropriately deliver to, i.e. individual actors or the special "followers" group for an actors) can be sent to the sharedInbox in bulk, but for private groups and some other special cases you may want to use direct delivery.