In software, as a project becomes larger, more documentation is necessary. And this relationship is not linear -- in fact, the amount of documentation over the size of the project will increase with the size of the project.
Similarly, as an organization becomes larger, there needs to be more structure. In a startup, you may not even need a real delineation of roles. But as the organiztation becomes larger and larger, more and more resources must be dedicated to "structural overhead." That is, stuff that doesn't "do" anything, but exists only for organization. Again, this relationship is more than linear -- the structural overhead necessary doesn't just grow proportionally with the size of the organization, but rather grows faster than proportionally.
As human's lives become more complex (just hunt and gather --> respond to emails, spend time with kids, write that report, practice the piano, etc. etc.) we also need more "structural overhead": to do lists, workflow managers, etc.
Is there a name for this general pattern, that as a system becomes more complex, the "overhead" also needs to become larger? And specifically, that this relationship is "more than linear," in the sense that the overhead necessary doesn't grow proportionally with complexity (or size), but rather grows faster than that?
EDIT: I'm receiving some answers about "diminishing marginal returns." The thing is, the marginal returns are not necessarily diminishing. In fact, it could be that we are experiencing economies of scale, and increasing marginal returns. More overhead does not equate to less efficiency, because it is possible that the extra overhead allows everyone to work more efficiently. What I'm looking for is a term like "____'s Law" that describes this.