Type hints in dynamic languages are great, but I wish they came with deeper integration into the language runtime for validation and for optimizer setup.
If I have a function that takes an int, and I write down the requirement, why should a JIT have to learn independently of what I wrote down that the input is an int?
I get that it's this way because of how these languages evolved, but it doesn't have to stay this way.
That was the original intent of mypy, to allow a subset of Python to be interpreted by a JIT or transpiled to a compiled, statically typed language.
The type hints proved to be useful on their own so the project moved past what was useful for that purpose, but a new JIT (such as the one the upcoming CPython 3.14 lays the groundwork for) could certainly use them.