> nothing about type annotations constrains Python code at all
Sorry, but this is just not true. Don't get me wrong, I write typed Python 99% of the time (pyright in strict mode, to be precise), but you can't type check every possible construct in the language. By choosing to write typed Python, you're limiting how much of the language you can use. I don't think that's a bad thing, but it can be a problem for untyped codebases trying to adopt typing.
Sorry, but this is just not true. Don't get me wrong, I write typed Python 99% of the time (pyright in strict mode, to be precise), but you can't type check every possible construct in the language. By choosing to write typed Python, you're limiting how much of the language you can use. I don't think that's a bad thing, but it can be a problem for untyped codebases trying to adopt typing.