I think the main point of the article is to shift type systems from being necessarily a part of the language itself to something that can exist outside the lang

I think the main point of the article is to shift type systems from being necessarily a part of the language itself to something that can exist outside the language and used to analyze it. For instance I once wrote a program which would infer types on a subset of Python and identify simple type errors without running it. That said there are languages which are more amendable to type checking. For example type checking a Ruby program which dynamically adds methods to a class.