Scribes don't really bother me, as I'm usually only moving the thumb or the fingers.
I don't buy the accuracy argument. As long as the driller is consistent they can be accurate.
I can see the point if several people are handling the ball. Just because a grease pencil leaves a bigger line doesn't make it less accurate. If you always drill to the outside of the line it's just as accurate - again that is assuming that the same person that laid it out is doing the drilling (or is at least familiar/comfortable with the technique of the person that laid it out).
It's no different that simple carpentry. It's always best for the same person to do the measurements and marking, and for one person to always do the cutting. My marking of 48" may be right in the middle of the 48" mark, somebody else may put the edge of the mark on the 48" mark. One cutter might always cut to one side of the mark, or may center the blade on the mark. As long as it's consistent the results are workable.
I've had scribed balls that have no less than 8 lines scribed on the ball.
I don't think if you are scribing that it is really necessary to draw a full line to mark the center of the grip line. Nor do you really need to draw 1" lines to mark the finger holes.
I've also seen scribe lines that are just as deep as the engravings on the ball!