While creating a calendar event if one adds a location to it, the event view allows later for triggering a Map app to display the location.
On the other hand one may not add a contact to a local calendar event, which may sound sane as informing the contact about local calendar event would be pointless. Still there is a value in having a contact participating in the event next to it, so user can trigger communication actions directly from the event view in calendar similarly to the Map display.