Facebook is largely a real person online person connector and a very crude version of everyday items such as photographs, calendars, small shops, etc.
Except computers lift the constraint of copying being expensive in the real world, while the internet lifts the constraint of copied object being expensive and slow to move around.
While Amazon provides inventory and delivery infrastructure to businesses and an internet storefront for customers, Facebook hardly provides anything that isn't trivial to copy - they rely solely on network effects and as a result - can largely be seen as a middleman parasite, worthy of extermination.