Because type script is a language not a language agnostic specification for languages. As someone who uses typescript a lot that probably is irrelevant. But if

Because type script is a language not a language agnostic specification for languages. As someone who uses typescript a lot that probably is irrelevant. But if I’m using Rust, say, then the typescript means I need to reimplement the spec from scratch. With OpenApi, say, I can code generate canonically correct stubs and implement from there.