It's only worthless if it's not true to possible positive outcomes for the reader. Whether or not it is an actual past experience of the 'author' or not, it can

It's only worthless if it's not true to possible positive outcomes for the reader. Whether or not it is an actual past experience of the 'author' or not, it can still serve its purpose (that's what myths are). In fact, you could argue that its anonymity increases its efficacy.