> As far as having many versions that all do the same thing, there is usually winners and losers over time. Because of this I believe that eventually the dependency graph shrinks overall.

That's... very naive. No one goes back and rewrites perfectly working code just to change a library. If it works don't touch it. Computers don't care, and if you rewrite it, you're introducing a bug. Also, there's plenty of new code to write! And oh yeah you have a billion little libraries, all used by an engineering culture constantly distracted by the new shinny, so you're going to be stuck with libraries that that haven't updated.

You're gonna have a bad time.