EDIT: Who would want to work someplace that will aggressively assert rights over your personal projects?
Let's assume Carmack happened to work on VR within a Zenimax office. We're talking about someone who created Armadillo Aerospace. If Carmack felt like developing VR outside of Zenimax offices, he obviously could have. So it must be true that Zenimax didn't actually help VR in any substantial way. Carmack's VR development just happened to take place within a Zenimax building. And now they're going after him for it, while playing it off like VR wouldn't have existed without Zenimax's contributions.
EDIT2: What convinced me was a thought experiment: imagine Zenimax without Carmack. Now think of all the ways that our imaginary entity could possibly contribute to the development of VR. At best, our entity provided a building for Carmack to pursue his personal interests in (a "mad scientist lab," as the Complaint calls it). Maybe some marketing, but who would deny that the hype would have rolled in regardless of whatever Zenimax did to help it along? Two seconds looking through a Rift is enough to transform anyone into an evangelist. The VR ball began rolling due to the efforts of Carmack, not Zenimax.
So, let's say you're Zenimax. You have Carmack working for you, working on all kinds of cool projects; whatever interests him. Choose your adventure:
- Stand to benefit by the halo effect of having a living legend on your payroll; a legend who gets the entire gamedev industry interested in projects happening at your company. Attract top talent by virtue of the buzz, and a creative's natural desire to be a part of cool projects. Your new top talent goes on to create many millions of dollars of value for your company.
- Try to assert control over whatever Carmack makes. Make it abundantly clear that no personal projects will be tolerated by any employee on Zenimax's payroll. Show the world that no one can work for you unless their sole ambition is to be a Zenimax employee. Convince every young hotshot college grad that it's a bad idea to go work for you. Lose whatever momentum you would have gained by attracting top talent.