One of the early uses of type systems was about performance of memory allocation, which brought massive performance improvements. Folks quickly realized that t

One of the early uses of type systems was about performance of memory allocation, which brought massive performance improvements. Folks quickly realized that they could be used to enforce invariants, which they're also really good at. Those benefits are orthogonal to dynamic vs. static type checking. Even with a dynamically typed language, you get massive performance, security, and correctness guarantees vs. an untyped language. There's huge merit in having a type system that provides all these benefits but still doesn't guard against runtime errors. Which brings me to my point: this person is clearly confused about the benefits of type systems, which don't require static typing to add incredible value.