Let's add another problem to the list: The packages uploaded to npmjs.org are typically not source packages, but "binaries" (in that they aren't source). They

Let's add another problem to the list: The packages uploaded to npmjs.org are typically not source packages, but "binaries" (in that they aren't source). They often contain minified JS files and no test suite, making them effectively useless for anyone that wants to build from source. Of all the language-specific package hosting sites, PyPI is the best I've encountered as they do proper source releases. Also, a package manager should not be a build tool. A build system should never require a particular package manager to be present. It's okay to say "you can optionally use this package manager to get all the dependencies needed to build", but it's not cool to say "you need this package manager in order to build."