The only optimization that DocumentSourceGeoNear has when calling doOptimizeAt() is splitForTimeseries(), which replaces the stage with $geoWithin, $computeGeoDistance, $match for min/max distance and a $sort. The $match stages use distanceField, which, outside of time-series, will stop being a requirement after SERVER-35581 is complete. This ticket aims to remove the requirement from time-series as well, possibly by projecting out the distanceField if it's the default after doing the $sort.