Buck (and Bazel) both have rules to run and cache arbitrary rules/scripts as part of the build, assuming they produce one output:

https://buckbuild.com/rule/genrule.html

Some other benefits that may or may not be important:

- Use the same build system for iOS/Android/Cxx/Python/D, etc.

- Integrates with editing in IDEs.

- Encourages modularization...more modules = more cache hits = faster builds