"What I don't understand, Tom, is why the USGA would acquiesce to a practice that enables the player to do an end-run around one of the fundamental skills of the game by allowing him to essentially perform his alignment from behind the ball, rather than above (and to one side of) the ball at address. That seems like a major abdication of the USGA's obligation to serve as the guardians of the game."
Shivas:
Clearly the reason they allow this is that they do not agree with you that this practice is some 'end-run' around a fundamental skill of the game. Perhaps they will view it that way some day but they do not now.
If they did view this practice as an end-run around a fundamental skill of the game they would probably view it as a violation in some way of Rule 14, most likely Rule 14-3a.
The USGA has deemed as non-conforming plenty of "equipment" and they have banned the use of many devices that they deem as "artificial" that constitutes some form of artificial "Assistance" or aid in making a stroke (a handwarmer is such an "artificial" aid and device).
A golf ball in play is not "equipment", and obviously they have never viewed it or anything on it (a line used for identification purposes) in play and during a stroke as an artificial "aid" or device that constitutes improper assistance that would violate Rule 14 ("Striking the Ball").
Don't forget that Rule 14 is not really all about just the act of aligning a ball or a player or his equipment, it's about the act of the player "Striking" the ball and that act is defined in the Rules of Golf as a "Stroke" (and that act is very distinct and different from the act of alignment).
So I suppose they feel it's not that important to be concerned about how a player aligns himself, his equipment or his golf ball in preparation for a stroke. What is important is that he use no artificial device or aid DURING the stroke itself.
Whether or not a golfer uses a line put on a golf ball for identification purposes as a means to align his ball to indicate the line for putting in preparation for a stroke he still has to make a skillful "stroke" at that ball to be successful and I suppose the Rules makers do not view that line as an artificial device or aid that constitutes "assistance" DURING a "STROKE" in violation or Rule 14.
Obviously you do, and just as obviously they do not agree with you and either do I.
In any case this practice is not a violation of the Rules of Golf and consequently players who use this practice are not cheating!
I think that pretty much explains all of this, Shivas. So what are you going to do now, just continue to argue that you're right and they're wrong?
Again, if you're so concerned about this practice make a written proposal to the USGA Rules Committee that you think this should be a violation of the Rules of Golf and see if you can get them to agree with you and adopt a Rule to that effect. That's what most people do who take some serious exception to a Rule of Golf or some practice that they think should violate a Rule of Golf.