There are significantly more package managers than apt and rpm. If languages each have their own package manager and library installer, it's only one thing for

There are significantly more package managers than apt and rpm. If languages each have their own package manager and library installer, it's only one thing for the writer of the library to deal with. If it was left up to the OS's package manager the writer would have to maintain 10 to 15 different packages, or get other people to. Would you rather deal with one gem, or bento package or one each of whatever rpm/apt/yum/pacman/brew/macports/pkgsrc/... use? If different OSs all converge to one package manager in the near future, then, great! we can use that. Until then though, I think language specific ones are just fine.