TypeScript is ECMAscript. You remove the types and you get pure ECMAscript, apart from some very minor - and nowadays unneeded - additions such as enums or namespaces.

TS also lets you do what Babel is for, translate the JS to earlier versions of JS. However, that has nothing to do with TypeScript itself, if your target runtimes support all the ECMAscript features you use you don't need to transpile, you only need to remove the type annotations, none of which are code (apart from the leftovers from early days mentioned above).

So you would need to complain about ECMAscript. The decorators in this release, for example, are there because it moved to a stage 3 ECMAscript proposal last year, which means TypeScript must implement it now - because TS ECMAscript and not its own language. So they need to support all of at least stage 3 proposals of ECMAscript.