Wei Wuxian nods his agreement. "It was really good. What do you think it would be like if people randomly busted into singing a song in the middle of a fight..or just walking down the street? I don't feel like you'd actually accomplish much."

Pretty sure he would be really distracted. Playing the flute is one thing..but to actually sing a song seems significantly harder to him. And of course this is what he takes from the movie.