I do not like the word sway as it relates to the golf swing. I think in general “sway” has a negative connotation and I’d prefer not to do it. There are a variety of shots in golf with a variety of optimal body motions. In general, the shorter the shot and swing, the less lateral shift, weight shift, etc… should happen on the backswing. I like an upper torso shift with the driver and potentially fairway woods and hybrids for most of my students. I always like a backswing pressure shift with a full swing, albeit the pressure shift is not seen by the naked eye or video.
Is a lateral movement away from the target on the backswing bad? It might create momentum for the downswing, but I do believe that it creates more opportunity for error and inconsistency for shots played off the ground.