What's the alternative? Promising a deadline they don't know they can hold? I don't know if you've noticed, but there's a pandemic outside, and every single supply line in the world is being affected one way or the other. If shipments have reached both the US and Australia (and other countries in APAC), chances are, every single country has at least a shipment on the way, and is either being held in customs or on a boat somewhere. Regardless, it's most likely out of HP's hands by now for the first shipment, and despite that there are entire weeks of lag between countries.

I know what you're going to say: the Quest 2 didn't have any of those issues. That's correct - at least, from what you've seen. Maybe Oculus was overtly cautious, and announced a date much later than they could have, just to be sure stocks would be ready. Well, I very much prefer a less clear communication and having the first shipments delivered ASAP than longer deadlines just to look like you own your communication. But maybe that's just me.