Its not just academic, because if you try to @include something from out of path in your code you'll not be happy. Moreover, 'zig build' is not the only tool in the zig suite, there's individual compilation commands too. So there are real implications to this.

It is also helpful for code/security review to have a one-stop place to look to see if anything outside of the git tree/submodule system can affect what's run.