TS doesn't "bin off" duck typing, it's a fundamentally structural type system. It's statically analyzed ducks, all the way down - when nominal behavior is preferred, people have to bend over backwards. Either you are using the wrong vocabulary or I don't think you've bothered to actually learn Typescript. In any case, it's the programming language that successfully brought high-level type system concepts like type algebra, conditional types, etc. to their widest audiences, and it deserves a ton of credit for that. The idea that JS and Ruby and Python and PHP developers would be having fairly deep conversations about how best to model data in a type system was laughable not that long ago.