I think in your first example, I can name a lot more bands that have been able to replace drummers and bassists than lead singers and guitarists, but all of the

I think in your first example, I can name a lot more bands that have been able to replace drummers and bassists than lead singers and guitarists, but all of them are considered rock stars. With a bit of unequal fame (well except for the obvious such as Santana). The crew is important, but so is the electric company that provides the power. They are, as you say, only there because of the rock stars.