of course python/ruby/javascript have succeed in bringing value to the world in general -- but in this thread we're focusing on production reliability, debugging, refactoring.
as we see, dropbox is proud to admit that they hired Mypy core developers and fund the project, but guess how much they spent on the mistake of using python?
twitter, famously an advocate for Ruby, spent an ungodly amount of engineering to work around ruby, hit a wall, and switched to JVM.
Just the fact that mypy and typescript exist and have exploded in adoption is proof that eng. teams very quickly hit a sand pit when using dynamic typed languages. Mypy being funded by dropbox, Typescript funded by microsoft, shows the level of investment needed to support these dynamic languages.