You really did not get it, did you? It does not matter, it does not matter ANYMORE if she can sing, can still sing albeit not 100%, or was able to sing a long time ago but now absolutely cannot anymore. She is Mariah Carey, she is a star, she still has a star wardrobe, an entourage, dancers, so she no longer need to be able to do anything. Being a star now involves... having been a star. Get it now?