Or the fact that Hugh did most of the bass studio work and they just had Alec for the live shows when they were the biggest band in the world?

Since the music industry began their have been songwriters, or session players who help create music but don't appear on the stage. Whilst I see your nostalgic viewpoint of the "idea" of a band, Mirielle, the reality has always been very different for anyone who makes it out of their local pub or club gigs.