I read the RoadMap (Thank you Marcus Smith) and came across this:
> An effort to integrate PyPI with the “The Update Framework” (TUF). This is specified in PEP458
I see a trend to immutable systems everywhere.
Not everywhere. Keep in mind that there are a *lot* of different usecases for packaging/deployment. Not just web app, not just CLI tools, etc... For example, it is common for modern end user applications to use an auto-update feature (e.g. chrome).