Shimming and polyfilling (i.e. ensuring standard functions are present and what not) sure. But I think most codebases avoid monkey patching (i.e. adding new functionality to built ins).

Maybe it's up for debate if the language itself guides people in that direction, but no one seems to do it anymore, so I personally don't think it does.

The new culture around modules actively shepherds people away from monkey-patching. Whether or not Webpack is considered "part of the language" for these purposes is fairly academic, but yes, the reality is that people don't really do that any more.