Questions About SIDS and STARS

I would try to make sure that the last waypoint of the SID, and the first waypoint of the STAR are the first and last waypoints of the plan (after and before the departure and destination airports).

The above quote is from another post and agrees with my understanding of the documentation.  If I have to enter these waypoints, it seems to me that VOXATC is not assigning SIDS and STARS but that I am.  VOXATC is merely repeating them in the clearance.

When flying an aircraft with a FMC, entering the SID/STAR waypoints after getting the clearance is easy and I have no problem with the VOXATC method.  However, when flying an aircraft without a FMC, flying unfamiliar SIDS/STARS from the charts is not easy.  Much easier if the waypoints are already in the GPS/autopilot. So, why not put all the waypoints of the SID/STAR into the flight plan in the first place? Is the sole purpose of the VOXATC method to get a more realistic departure and approach clearance?  If I were to put all the waypoints of the SID/STAR into my flight plan and not just those noted above, would VOXATC clear me for the SID/STAR or would it ignore SIDS/STARS?  If I don't put all the waypoints in the flight plan will VOXATC give me any different instructions after take off or during approach than if I put them in?