Going way back, other examples include Cliff Richard and David Essex. An exception to this is Queen whose synergy grew to the heights of unparalleled entertainment, both visually and musically. Many 'entertainers' have tried, including Elton John and Robbie Williams, but none have come close (in my opinion) to those four talented people in a harmonious direction.
Except, perhaps, The Beatles with their song-writing talents and harmonies, who exempted themselves by shifting their style (and possibly the LSD was a factor in that). But, unlike Queen, The Beatles were talented people with ambitions in different musical directions.
And the other exception: the constantly shape-shifting David Bowie.
This theory is more difficult to prove for 'mentored' artists but if we think back to the X-factor final between Joe McElderry with a perfect voice that won him the competition and Olly Murs whose voice was good and gave him in second place - who really won? Olly Murs had the energy and obvious enjoyment of performing for his audience and is as popular as Joe McElderry is obscure - thus illustrating that passion beats perfection.
Beebopalula