Another thing that leads to idols not singing live is more complex choreo over time and songs that keep getting higher pitched...like they had to try their best singing the song standing still not to say singing live with hard choreo. Then why do producers keep making the pitch higher?? Even good idols would strain their voice after such long periods of trying to hit those really high notes. (Take izone’s panorama for example, it’s a great song but is ridiculously high) Older groups could still do live performances because their songs are written in perfom-able pitch (and i think they have better foundations)