Feint from windup

[LakeErieUmp]

CoachJM - Because, traditionally, the set position was keeping runners on/throw back to base while the windup was concede the steal. R3 will take X lead with the pitcher in the set but will take X+ with the pitcher in the windup. If the pitcher can basically feint a pitch by stepping toward home but then continuing to a throw to third there is no difference between set and windup. That being the case, why would a pitcher want to use the set which takes away some leg kick and power behind his pitch? It seems the feint in a SET was read between the lines to let a pitcher - holding the runners back - not have to waste time throwing to the base he's feinting to.
But if the consensus is otherwise I'll go with what you all say from your better experience than mine.