That kind of precision isn't necessary for tracking position accurately for VR/AR though, Hololens' current system is pretty damn good and I'm sure internally it's improved a bunch as they roll out their own VR headsets too.
It absolutely is needed for many AR applications. VR is a bit more forgiving, particularly if you are talking consumer and games. Any time you need maintain a relationship to the physical space you are in you can run into trouble though.