Your view assumes that all language-level packages are already so mature that each of Debian, Gentoo, Arch, brew, MacPorts, etc. have a person whose responsibility it is to make a system-level package for that language-level package. What about new packages? If language packages are to be distributed on each system using the system package manager, then the way to get a new package into the hands of programmers is to a) write the package and b) before anyone has used it, spend a couple of years convincing a person on each system to create and maintain a system package for this new and completely unused Ruby/Python/Perl package. I guess that's reasonable if you're dead set on only using software that was written ten years ago.