A consumer product like the Rift is an entirely different proposition with an entirely different set of challenges. The Open Compute project was essentially Facebook giving away some of their data center designs and specifications (mostly things like server racks and power management), with a few other companies joining the initiative but with none of the designs actually being used on a significant scale.
How much experience do they have marketing that tech? I've never heard of someone selling a Facebook-brand router. The few times I've heard of FB involved in an actual product, it tanked or disappeared, never to be spoken of again.
Facebook phone, anyone?
There's a world of difference between a potential item, like the FB phone and an actual, demonstrated item, like the Oculus Rift, so they might get some points there.
They have a lot of XP in building real physical shit these days.
Scaling traffic is a non-issue for them.