The reason why the masses should consume is to motivate them to work. And the reason why having a large amount of people working is that human work has been producing a surplus basically since the dawn of civilization.
This surplus is partially shared but tend also to "trickle up", contrary to some weird beliefs, as can clearly be seen almost everywhere you look.
But if you imagine a sci-fi world where machines can build and do everything humans can do, the concept of a human-centric economy would be pointless.
Machines don't need to be motivated to work, they just need energy, materials and obeying to whoever controls them.
This kind of economy would be less abstract and more directly related to physics.