What on earth am I talking about here? This is how I think about the roles of the various instruments. The rhythm section, consisting of bass and drums is the skeleton, the bones, and everything else is the flesh that hangs off the skeleton.
So the real “song” is defined by the rhythm section. A vocal track should have no problem existing inside this space thus creating “the song”. And indeed it is all empty space in there. The other instruments – the acoustic guitar, electric guitar, keyboard, organ, solo and orchestral instruments, backing vocals and choir – all are the flesh and muscle and organs (hah) that exists inside the skeleton, and must not conflict with the lead vocal or each other!
This paradigm, these new wine skins, must inform how everyone thinks about the song to include how it is played and how it is mixed. The mix must begin with the kick, snare, hat, etc. and then go to the bass, and then the other instruments. They can be sub-mixed in groups (the rhythm section in Group 1-2, the instruments in Group 3-4), so that the vocals speak, but the only thing that can conflict with the vocals are the instruments, not the rhythm section.