It's not a solved issue, as others have pointed out. To elaborate, most packages are not maintained continuously. Some don't get updates anymore and some get up

It's not a solved issue, as others have pointed out. To elaborate, most packages are not maintained continuously. Some don't get updates anymore and some get updates that break older versions of Python. The authors of these libraries definitely aren't rooting out all the problems that can occur due to mismatched versions. And when you change one library, any other related library can be affected. It's like solving a puzzle sometimes. In many cases people throw up their hands and say "forget this, I'm not upgrading anything!" This is also the big driver of solutions like virtualenv and Docker. All languages have this issue to some extent but Python breaks stuff more often than anything else I use. I don't especially like language-specific package downloaders either but that's not a Python-only problem, and there are tradeoffs to pushing the work downstream into more stable systems.