[scikit-learn] Is there any official position on PEP484/mypy?

[Gael Varoquaux]

I am still worried that this is going to add even more complexity to
contributing: people will contribute without knowing type hint, CI will
break, they won't understand why it breaks, won't be able to reproduce
it, and it will stall PRs.

Can you summarize once again in very simple terms what would be the big
benefits?