That's not actually what I was thinking of, but it's related. I was thinking more of the hard work of making sure you have a compatible set of library versions

That's not actually what I was thinking of, but it's related. I was thinking more of the hard work of making sure you have a compatible set of library versions that every app in the repositories can link against, with whatever patches they need to make that work, to provide a complete working system for the user - including end user apps like mail clients, browsers, editors, the whole shebang.