The problem is that Rod's form is really good and his points of explanation are the best I have heard.
Unfortunately, when a person varies from that form and shot execution it simply hurts accuracy potential. Of course there are various things one could do differently than Rob and still shoot well, such as shoot faster or slower, or cant the bow; but such things as trying to hold the bow up after the shot, using a "hard" anchor, etc. can only hurt ultimate accuracy potential. Take a look at some of the videos on this site of Howard Hill and some of his "old time" buddies. Except for the canting and speed of shooting, their form looks very, very similar to Rod's.
That said, I have personally witnessed people who have horrible form by any standards and who are plenty accurate enough at unknown distances out to 25 yards or so to be very effective at hunting, and even shoot very respectable 3D scores. However, using Rod's textbook form, or something very close, is surely going to make it easier for anyone who is trying to improve his/her shooting.
Don