when you use offline calendar you don’t have any way to export your calendar if you don’t sync it. At the same time, it’s not possible to import an ics file with more than one event (it’s possible but that will import only the first event).
So the idea is to be able to import/export calendar to/from Calendar app as ics file.
It seems Etar project team is working on this kind of thing for a while… but for a long while (3 years)…
