That's highly debatable. We moved back to ES after using Typescript for years and couldn't be happier. We're much more productive than we were with Typescript, and that's with people that know the language. We get much of the benefits of Typescript by just using a jsconfig.json file in our project and using VSCode. The Typescript language service will typecheck JS code if you want it to.

And there is a big upfront cost for onboarding developers with Typescript and Angular.