That makes no sense. People don't care that much about how good music or songs are. If not, why do you think the songs on the best playlists keep changing? What matters is being able to maintain the same knowledge and talk about that music or song with someone. So AI-generated music can have no value. In music, narrative isn't something supplementary. People want narratives and music is the medium for that. (But outside of Spotify, maybe this won't be the case. People aren't interested in the narrative of such music as background music or OSTs.)

because all narratives ever written about/in music are 100% true and no one ever made up a story for entertainment purposes.

AI-generated music will just have AI-generated backstories to provide a narrative and story behind the lyrics for people that want that.

People want music for different reasons. Some just like it because it sounds cool.