I think it'd make other things impossible too. One project I help maintain is C++ and is mainly so. It optionally has Python bindings. It also has something like 150 options to the build that affect things. There is zero chance of me ever attempting to make `setup.py` any kind of sensible "entry point" to the build. Instead, the build detects "oh, you want a wheel" and generates `setup.py` to just grab what the C++ build then drops into a place where `build_ext` or whatever expects them to be using some fun globs. It also fills in "features" or whatever the post-name `[name]` stuff is called so you can do some kind of post-build "ok, it has a feature I need" inspection.