Zenimax, an investment vehicle for Providence Equity Partners, is literally run by actual lawyers. In the early days of Oculus, Carmack tried to get them interested in VR, and they wanted nothing to do with it. Now all of a sudden Oculus is a result of their tech.
They wouldn't even have the slimy case that they have, if not for the fact that Carmack and others used to work there. People can debate the legal technicalities all they want, but the plain, everyday explanation of what happened is that some lawyers figured out how to retroactively create and profit massively from a virtual non-compete that never existed.