A stock Unreal Engine project is several hundred gigs, consists of multiple solutions, multiple languages, and I would classify as large personally.
Without some kind of indexing it’s very awkward to work with and very slow. To work with LLMs and Unreal projects we create a local index, that index file alone is 46GB.
Without distributed compilers and caches it can take multiple hours to compile the main solution per platform (usually PC, Linux, Xbox, PlayStation, Switch, and sometimes mobile).
So the codebase easily fits on local storage so long as you don’t count assets (those are several TB) and extra so for source assets (10s of TB), and that’s per stream per large project.
Anyways, point is I disagree and think Unreal Engine is an example of large codebase that fits locally.
Listen, I am a rails developer, so a monolith doesn’t scare me, and yet, there are limits. Why does it need to be a multi terabyte monolith?
People usually mention git-lfs at this point, but that is always annoying to use in practice. There is also shallow-clones and sparse-checkouts, but these only mitigate the problem as there is no way around cloning at least one revision completely with git.