Are they actively blocking the other HMD's or just not supporting them with drivers, etc? I know they locked it down at one point with DRM, but quickly backtrac

Are they actively blocking the other HMD's or just not supporting them with drivers, etc? I know they locked it down at one point with DRM, but quickly backtracked. Revive is a free option, that works with the Oculus Store and the Vive but that's obviously not as nice as native support from Oculus.