Software typically evolves and grows and changes over decades. There very often isn't any point where you can go "for our next project we choose X". Each new pr

Software typically evolves and grows and changes over decades. There very often isn't any point where you can go "for our next project we choose X". Each new project is a feature using 90% of some existing huge codebase. "Starting fresh" is something many (most?) companies simply never does, over decades. (And if they attempt it is often an all out disaster..) 2011 is fairly recent in this context, and many popular libraries were not available on Py3 until much more recent than that, even if you have the rare luxury of starting fresh.