Don't forget the classic non package maintainer mistake of thinking policy = package file type/format.

Its pretty trivial to "force" a rpm to install on a Debian box. That doesn't mean that magically any of it will follow Debian policy, any of the paths will be correct, any of the dependencies will be correct. But technically files can be thrown onto the filesystem, even if they can't actually be used where they land. And vice versa, if you shove a deb onto a Redhat box.

My biggest "NIH" surprise is GNU has this and the emacs package system and at first glance they have nothing in common. The idea of installing a local copy of Rails or Leiningen off Emacs MELPA is kinda weird. I wonder if emacs twenty...something will use a user level version of this system. That would be interestingly consistent.