I believe that Facebook's acquisition strategy follows Microsoft's 1990s playbook, even if that's not the conscious intent.

Facebook's core product is now in a similar position as Windows was twenty years ago. The near term will require pleasing shareholders by milking the monopoly, but the company is worried about missing future trends. To avoid that, they buy interesting startups with promises of independence. For Microsoft, that included companies like WebTV, Hotmail, Softimage, Bungie...

Compared to Facebook's acquisitions, Instagram is more like Hotmail whereas Oculus is more like WebTV -- a bet on an emerging technology that holds a lot of potential even though it's not obvious how it will integrate into the parent company's core product. (Yes, there was a time when "web on a TV" seemed like a revolutionary idea not unlike "consumer VR" today.)