I know I shouldn't get into this thread, but I'm extremely curious: what did you expect should have happened? I mean, literally, what do you mean by "just work", what work did you expect a type checker to perform if not to show you errors?

I expected a reasonable amount of reasonable errors, not 60k+ errors most of which are import-error, even though the code runs fine.

Its the fault of the tool that the codebase had lots of errors?

I would say it's the fault of the ecosystem. Hopefully it will get better as libraries adopt type hints.

That's incremental adoption for adding type hints, not for adopting this particular tool in an already-type-hinted codebase.

…how else would it work?

What does "just work" mean? You are comically obtuse.