The current CPython build system is antiquated and makes cross-platform builds difficult (in my experience). There have been unofficial CMake implementations but they are either outdated, abandoned or just unusable.

Adopting CMake has many benefits, here are few:

1. Simplifies cross-platform builds and inclusion of CPython in other projects as subdirectory/subproject.

2. Automatically generated builds for any CMake supported OS'es, no need to maintain an unique build system for each OS, only the CMake script.

3. Faster. Just the configuration process in current build system for Unix is super slow, making testing changes slow and painful.