It's a valid hypothesis, but without empirical data the question is not easy to settle (and neither Carmack nor Blow are notable authorities on systems that have to be maintained by changing teams of hundreds of people that come and go, maintaining a large codebase over a couple of decades; if anything, most of their experience is on a very different kind of shorter-lived codebases, as game engines are often largely rewritten every few years).
Also, the question of inlined code mostly applies to programming in the small, while modules are about programming in the large, so I don't think there's much relationship between the two.
> neither Carmack nor Blow are notable authorities on systems that have to be maintained by changing teams of hundreds of people that come and go
Most systems don't have to be maintained by hundreds of people. And yet they are: maybe because people don't listen to folks like Carmack?
We like stories about huge teams managing huge codebases. But what we should really be interested in is practices that small teams employ to make big impact.
I didn't mean a team of hundreds maintaining the product concurrently, but over its long lifetime. A rather average codebase lifetime for server software is 15-20 years. The kind of codebase that Carmack has experience with has a lifetime of about five years, after which it is often abandoned or drastically overhauled, and it's not like games have an exceptional quality or that their developers report an exceptionally good experience that other domains would do well to replicate what games do. So if I were a game developer I would definitely be interested in Carmack's experience -- he's a leading expert on computer graphics (and some low-level optimisation) and has significant domain expertise in games, but he hasn't demonstrated some unique know-how in maintaining a very large and constantly evolving codebase over many years. Others have more experience than him in domains that are more relevant to the ones discussed here.
Also, the question of inlined code mostly applies to programming in the small, while modules are about programming in the large, so I don't think there's much relationship between the two.