My claim comes from having built large scale systems with and without TS. I have the scars from working without it and I'll never do it again if I can help it. I'll also say that it's possible to write bad buggy code no matter what tooling you use. It's a "pit of success" thing for me. I want to at least make sure the super dumb stuff doesn't make it through.

IMO you should use all the TDD, documentation, and code/design review in ADDITION to a type system.