Until you realize that FB has no API to get events out of FB. FB might be useful but it's the same usefulness as having an email thread with a calendar invite. They don't let you export your event data in any meaningful way to keep you on the platform.
It's not just about events automatically appearing. First of all, I'm not sure of a way to do that without individually exporting events, maybe if I setup FB emails for events, I could get GMail to auto-add them, but I don't use GMail so it would take more setup to ingest invites automatically. But even then, there's no way to RSVP inside the calendar invite itself. The interface is opaque, they let you read their data, but not interact with it in a programmatic way despite it being _your_ friend network and _your_ event.
