Does Python work fine without all that? If it did, validation and type-checking tools like mypy and pydantic (or the recently introduced Typing in the standard

Does Python work fine without all that? If it did, validation and type-checking tools like mypy and pydantic (or the recently introduced Typing in the standard library) wouldn't exist. Or having to write lines and lines of checking code because someone else (also me) forgot to annotate the expected types of some parameters.