I saw a talk by an npm developer who dismissed type checking as "just another kind of unit test" for your code (and advocated instead dynamic typing and manual

I saw a talk by an npm developer who dismissed type checking as "just another kind of unit test" for your code (and advocated instead dynamic typing and manual unit tests). It bothered me enough to think about what was wrong with what he said long after the talk. I realized the difference is type checking takes the place of infinite numbers of unit tests: unit tests only assert an "exists"; type checking proves "forall". The linked article, however, is a whole other level of incorrect thinking and drivel.