@jenniferplusplus @darius @thisismissem @mauve activities do too, as well! or they should. activities are also objects.
the advantage of thinking in terms of activities is that it's a better representation of reality, with AP serving as a specialization of LDN (Linked Data Notifications), you're basically notifying your followers/audience/recipients that "something happened". it's the reason we POST Create activities and not just raw non-activity objects.