Fairy tales usually exist to instill a set of values or drill "common sense" into someone at a young age. e.g Don't go out into the woods alone or a big bad wolf will get you, don't eat yellow snow, there's a man in the sky who watches you and you won't get into his gated retirement complex if you're bad etc etc
If those values are deemed either culturally obsolete or contain abhorrent garbage then it is natural that the stories will evolve or disappear.
To give my favourite example of this, compare Geoffrey of Monmouth's stuff with Le Morte d'Arthur and Chaucer's stuff. Wildly different, highlighting different aspects of people. Some in an attempt to shoehorn their desired contemporary ethics (e.g. the trope of the purity-driven chivalrous knight) others because they were crap writers and felt that every story needs a weepy tragic romance involving dishonour and infidelity. *glares at Chrétien de Troyes*
Which of course leads us to the final evolution of that fable, Monty Python and the Holy Grail - which as everyone knows, is both canonical and historically accurate, and completely within the spirit of the age in which it was created.
If those values are deemed either culturally obsolete or contain abhorrent garbage then it is natural that the stories will evolve or disappear.
To give my favourite example of this, compare Geoffrey of Monmouth's stuff with Le Morte d'Arthur and Chaucer's stuff. Wildly different, highlighting different aspects of people. Some in an attempt to shoehorn their desired contemporary ethics (e.g. the trope of the purity-driven chivalrous knight) others because they were crap writers and felt that every story needs a weepy tragic romance involving dishonour and infidelity. *glares at Chrétien de Troyes*
Which of course leads us to the final evolution of that fable, Monty Python and the Holy Grail - which as everyone knows, is both canonical and historically accurate, and completely within the spirit of the age in which it was created.