I'm not confusing anything here. Unless a language has a platform specific API it typically gets bundled into the language specifications itself to ensure consistent interfaces and to force implementations to match a set standard.

C++'s STL is part of its specification. Python has a library reference outlining the interfaces their standard libraries must include.

You're still thinking in browser world. In a browser world a browser is a platform and has to provide APIs to allow JavaScript to interact with its elements. Today this isn't always true. Today you have node.js and several other execution engines that allow JavaScript to run anywhere much like other languages. It's time the standard reflects that new reality, in my opinion.