The industry I am in is extremely conservative about its upgrades and changes. Between that, our custom software interfacing with the 800 pound gorilla for our market, and a few other things, we're behind.
Now, this software depends on a very specific version of ArcGIS. Desktop, not Pro. Not just version 10. Not just version 10.2. But version 10.2.1.
If you go look at ESRI's page for Python and 10.2.1, it says, in large and bold letters (which is something ESRI doesn't do in its documentation very often), NOT TO UPGRADE OR CHANGE PYTHON VERSIONS, EVEN A TINY BIT.
And that version is 2.7. I couldn't even get pip working when I wanted to install a very old version of lxml I wanted.
I guess what I am getting at is, as a language becomes successful and has market penetration, it also seeps down, way far down, in the chain of dependencies. It's the price of success, essentially. I think language maintainers should really pay more attention to that. Just as you know how a program ends up sticking around longer than you originally thought, so too do versions of your language. It is in some ways akin to trying to explain to da Vinci that very far in the future, some of his artworks will adorn clothing and coffee mugs: the good stuff just gets to places you would never dream.