Semantics comes in. Changing the seatpost setback to compensate for less than ideal sta DOES affect rider reach AND fit to the handlebar...common sense. If does not affect 'Cervelo's definition' of reach however...you are quite correct.

What you repeatedly mentioned however is pertinent...and that is STA. There is no escaping the importance of it which is perhaps the biggest misunderstanding in this thread. For those analytic types which includes you, me and rruff, best way to determine how well a frame fits is to plot it in X,Y coordinates as rruff stated...using a simple CAD program. Cervelo's attempt for the layperson is stack and reach. This basically sets the A or primary datum as the BB centerline.