Most VR headsets don't work at all on Linux, and for those that do, most games don't work anyway. For those that do work, they are unstable, and SteamVR itself is unstable and prone to crashes. Even when things work for a while, the frame rate is lower than on Windows, which is much more important for VR games.
So as much as flat games work perfectly on Linux nowadays, it's just not there for VR.