Except that the rules permit you to repair the damage in the case that someone steps on your line or to request relief from the committee if it cannot be repaired (Decision 16-1a/13).
You guys are missing the point (MEfree, this isn't personally aimed at you, yours was just the handiest post to quote on the topic). It's not a question of whether it usually improve your make rate, it's enough that it might help you make a putt that would otherwise not have gone in. In the situations where that happens, you have gained an advantage that has been deemed unwarranted. Thus, there's a penalty for it. It's a clear rule, it's not difficult to avoid, and it's never going to invite ambiguity in enforcement. I don't see the big issue.
I understand what you are saying and agree that it is a clear rule that is not difficult to avoid most of the time. Still, I had an incident where I broke the rule when my playing partner was slow getting over to take the stick out on a long putt where I wanted him to tend it but putted too quickly. The ambiguity here is what score do I turn in for my handicap? I enforced the penalty on myself, but some might call this sandbagging as the chances of this happening in competition are pretty remote.
It is also one more rule for everyone to remember. I knew it was a penalty, but didn`t remember if it was 1 stroke or 2, so I asked one of the guys in the pro shop who said he wasn`t sure who asked the other pro who first said 1 shot, but then corrected himself as I was leaving.