> The fact that there are such libraries in existence means that there is no pain associated to this particular activity

I can say the same about Rails + RSpec. It exists therefore it's good.

> Mocking dynamically typed languages is monkey patching, something that the industry has been moving away

That's a reach. There are millions of javascript/python/php/ruby/elixir devs that don't use types or annotations. They mock. "The industry" isn't one cohesive thing.