I sometimes wonder if this is how industries end up not innovating or solving obvious problems for decades because they get strangled with bureaucracy which doesn't solve the original problem highlighted in his own example (vendor choosing to ignore to patch a vulnerability).
I'd consider static type checker as optional if you are playing around with small or throwaway scripts, but for any half serious project, it should be a requirement.
IME I don't consider it slow, and it's definitely not visibly slower than pylint, flake8, or similar tools for other languages.
Dropbox, which has one of the biggest Python codebases, uses it, and most mypy maintainers including Guido work there.