[eska]

If all of your dependencies need to use the same build system as your project then your build system/process is defect anyway. It should be possible to invoke a foreign build system as part of your build.

[steeve]

and it would be terrible for hermeticity and reproducibility, nix tries very hard and gets mediocre results

perhaps, just perhaps, why people go through the trouble not because they are idiots but for actual engineering reasons