The Vive fundamentally needs SteamVR to work. SteamVR is where the tracking data is collected and made sense of. Another critical function that SteamVR preforms is distorting the output of the PC to match the Vive's lenses. If you just pipped unaltered video into the HMD it would look like gibberish. You can use the Vive as a monitor using tools like Virtual Desktop but like all Vive applications it requires active tracking thru SteamVR.