Is a "general consensus" tool more useful than a personal tool?One reason, a general consensus can be reached much easier, two, scientific theories can be changed (and will be ) with new evidence. Myths have the unfortunate habit of hanging around long after their real usefulness, as they are not based on evidence, but on faith and/or fiction.
Edit: I would propose that, rather than being unchanging, the myth has a new, distinct and unique meaning for each person who reads it, each time they read it.