I’m probably talking about something different than what you think.
Please review the technical material in the chapter “VR Technology Explained” you can find here:
My 2070 SUPER VR settings and suggestion (Reverb G2 - WMR)
TL;DR: reprojection of the render view image is intrinsic to the VR technology regardless of motion smoothing, so as as to position the view at the correct location due to the head moving from the time the application starts rendering the view to the time it displays in the headset (motion to photon latency).