The show isn't a singing contest though is it, Barlow seems to focus on the voices but it is about the X-factor, are you marketable to the public? have you got the charisma to keep people interested in what you do? will people care about how you do?
Per the comment above, the last lady, the prison officer who sang Beyonce, was absolutely brilliant, she'll get through hopefully but she'll never win, she's just not marketable enough unfortunately.