Earlier quoted context omitted.
Oculus was funded by a kickstarter. I think Notch personally contributed. Having given money to help a company develop their core technology is a little different to "not even involved beyond having read about it".
But that isn't what a Kickstarter buys you. You get rewards and you get to help fund the initial vision. (up to the scope of the Kickstarter, fulfilment of rewards, etc.) In any case, if making awesome VR a reality was Oculus' vision, they can make a pretty good case for that vision being well served by the resources of Facebook. At the end of the day, what are people afraid of? That the newest action games won't be…
That said, I personally don't know if Facebook is going to mess up Oculus. I imagine that what people are worried about is that Facebook will push for Oculus to be used for social VR and will largely ignore games. VR gaming requires high quality sensory experience in a dynamic environment with fast player movements. Social VR is probably going to be way, way more static, (but will have other demands like monitoring body position, face scanning, etc.)