I read this today in an article by David A. Christianson, CMW21:
In all this discussion, the term “watchmaker” means the man who repairs watches — not the man who works in a watch factory. The factory man need not know anything but his one limited subdivided portion of the watch. The watch repairer, on the other hand, must know how to make almost any part of any watch when necessary. This act justifies the apparently paradoxical statement that the man who repairs watches — and not the man who works in the watch factory — is a watchmaker. To say watchmaker for watch repairer is correct and in accord with trade usage.
From John J. Bowman, Chairman, Education Committee, Horological Institute of America.