For an edge case: people will be impressed and interested if you tell them that a piece was painted by an elephant, and then suddenly unimpressed if you tell them you were lying about that. So one function of art is as a sort of experiment, like the art is experimental data, where authenticity matters, because the interest is in the demonstration of a perspective, the reactions of an artist in the situation. Consider noir: a movie is much more plausibly authentic noir if it was made before about 1963, that is, if it was made by actors and directors who actually wore those hats (and lived through other tropes). Later on, it's imitation, regardless of how accurate: the experimental data is invalidated, it doesn't (seem to) mean so much.