Well, broken builds are bad, but this can happen with any package management system right? Any open, easily updatable package management system will encounter t

Well, broken builds are bad, but this can happen with any package management system right? Any open, easily updatable package management system will encounter these problems. Only testing and curation to ensure there's no broken builds will solve the broken builds issue. As for bloat, software reuse should be at least an option, a better phrase is "Reinvent the wheel, only when necessary". You're example of Maven is a much less flexible system, although it promotes stable API's. The main problem with only allowing one version of a dependency in a project is that dependencies aren't isolated per package, which means with lots of libraries there's no way to guarantee that they all have the exact correct version of the library they need, which will inevitably result in weird errors. The only reason libraries should use the exact same version is if they're communicating like you mentioned, soooo why not just explicitly state that dependency too then?