I'm curious about python being on that list. I worked with python on multiple applications, some fairly large (500kloc), over 10+ years with multiple version upgrades without issue. I always considered python's backwards compatibility to be one of its strengths. That was why the python-3 was such a big deal, it would break backwards compatibility which had always been a top priority.
It's all much better now, especially since pip can (and does) install per-user. Of course, for anything non-trivial, you'd want a virtualenv anyway, and then you're dealing with a single place for all dependencies, and (usually) pinned version numbers.
I am missing something?