Great post. I think this is the fundamental thesis proposed by Abelson and Sussman in SICP. You build a system in layers, each relying on the one below.
The reason you do this is to manage cognitive load in humans, not "coupling" in computers.
First, we want to establish the idea that a computer language is not just a way of getting a computer to perform operations but rather that it is a novel formal medium for expressing ideas about methodology. Thus, programs must be written for people to read, and only incidentally for machines to execute. Second, we believe that the essential material to be addressed by a subject at this level is not the syntax of particular programming-language constructs, nor clever algorithms for computing particular functions efficiently, nor even the mathematical analysis of algorithms and the foundations of computing, but rather the techniques used to control the intellectual complexity of large software systems. [1]
The reason you do this is to manage cognitive load in humans, not "coupling" in computers.