They cannot add it in other people's libraries.
> did not stop Python rising to conqueror the world
I wasn't talking popularity, I was talking maintainability. Python is not a stellar example of maintainability (source: maintained the Python API for a timeless debugger for 5 years).
Python's ubiquity is unfortunate, thankfully there seems to be a movement away from typeless signatures, both with Python's gradual typing (an underwhelming implementation of gradual typing, unfortunately) and Typescript.
Does it matter that much how the internals of someone else's library are implemented? The tooling will tell you the types anyway and module interfaces will have type signatures.
> Python's ubiquity is unfortunate,
Well that we can agree on!