Why are we so much bigger than atoms?

Quick notes from Schrodinger's 'What is Life':

We combine two paradigms:

Quantum world: Operates on the nanoscale. Energy is quantized, which means continuous noise will not constantly disrupt processes or destabilize structures. Therefore, you can do useful things.

Continuous world: Operates on the macro scale. Due to the law of large numbers, noise is scaled down by sqrt (number of atoms involved). Therefore, continuous noise is less of a problem and you don't need to rely on quantum effects.

We multicellular organisms are able to operate on both of these scales. I'm not sure how to justify why this is important, but it seems quite useful! 

Footnote: In the quantum world, the kBT unit of energy rules triumphant - in the nanoscale, many different types of energy become comparably large to that unit. It's on these energy quanta that the cell operates.