As someone who has worked in the space for a while and been heavily exposed to nix, bazel, cmake, bake, and other systems, and also been in that "passion project" role, I think what I've found is that these kinds of systems are just plain hard to talk about. Even the common elements like DAGs cause most people's eyes to immediately glaze over.
Managers and executives are happy to hear that you made the builds faster or more reliable, so the infra people who care about this kind of thing don't waste time on design docs and instead focus on getting to a minimum prototype that demonstrates those improved metrics. Once you have that, then there's buy-in and the project is made official... but by then the bones have already been set in place, so design documentation ends up focused on the more visible stuff like user interface, storage formats, etc.
OTOH, bazel (as blaze) was a very intentionally designed second system at Google, and buildx/buildkit is similarly a rewrite of the container builder for Docker, so both of them should have been pretty free of accidental engineering in their early phases.
Managers and executives are happy to hear that you made the builds faster or more reliable, so the infra people who care about this kind of thing don't waste time on design docs and instead focus on getting to a minimum prototype that demonstrates those improved metrics. Once you have that, then there's buy-in and the project is made official... but by then the bones have already been set in place, so design documentation ends up focused on the more visible stuff like user interface, storage formats, etc.
OTOH, bazel (as blaze) was a very intentionally designed second system at Google, and buildx/buildkit is similarly a rewrite of the container builder for Docker, so both of them should have been pretty free of accidental engineering in their early phases.