Was not setuptools the single tool for package management? It provided both the installer plus hooks to define packages and manage the install (plus eggs to try to manage the path). That doesn't mean the choices were the right ones (the package definition being the only thing to survive), but it seems that while cargo has the mindshare for pure-rust, when there's the need for integration with other ecosystems (as is the biggest challenge for Python), people need to switch to using meson or bazel and there appears to be some issues there.
Kind of, except that setuptools was never part of the standard library or standard distribution of Python. So it suffers/suffered from the same bootstrapping issue as the rest of Python packaging.
