Again, you're solving for a very specific type of interaction that is not necessarily needed.
Does every virtual web app need server authoritative position? No. We could imagine a world where much of the physics and rendering is client side for most apps.
Does it make sense that every virtual web app should pay for low latency server authoritative position? Also no.
Sure, some apps will want this level of synchronicity and maybe there's a place for another web standard but its silly to say that http is not feasible or that this is the only way web VR should work.