@nprofile1q... @nprofile1q... The blog post in question does not look at Smalltalk or Objective-C at all, did you even read it at all? Heck, neither are even mentioned. Instead, it looks at the actual research.
And yes: the documentation effect is powerful and is actually well supported by the research. Unlike the safety effect, which is not just not supported, but actually consistently contradicted by the research.
Static typing is a convenience feature, not a safety feature.