> If you take multiple systems and make them work in concert, you just get a bigger system.
The conclusion may be wrong, but a "bigger system" can be larger than the sum of its constituents. So a system can have functions, give rise to complexity, neither of its subsystems feature. An example would be the thinking brain, which is made out of neurons/cells incapable of thought, which are made out of molecules incapable of reproduction, which are made from atoms incapable of catalyzing certain chemical reactions and so on.
This is just emergence, though? How is emergence related to completeness?
This happens over and over with the relatively new popularization of a theory: the theory is proposed to be the solution to every missing thing in the same rough conceptual vector.
It takes a lot more than just pointing in the general direction of complexity to propose the creation of a complete system, something which with present systems of understanding appears to be impossible.
> How is emergence related to completeness?
I didn't make that argument. I think, the original conclusion above isn't reasonable. However, "a concert" isn't "just" a bigger system either, which is my point.
It just depends on your definition of system, doesn’t it?