This is a good type of feature. I've been super happy that WhatsApp finally added events recently, it's made seeing who will be coming to an event or not so much easier. Them adding polls a while back had already improved that a bunch, but this is even better, since it sends reminders and so on.
Of course Apple could use this to do vendor lock in (only apple users can create invites), but since anyone can join them I don't see it as a large issue.