At least for Emacs, dealing with big codebases isn't a problem. Modern approach to dealing with this is to use language servers. This is also what VSCode does

At least for Emacs, dealing with big codebases isn't a problem. Modern approach to dealing with this is to use language servers. This is also what VSCode does. So, suggesting you have better autocompletion in VSCode vs Emacs (or Vim) is just a sign of not knowing how that works, because they are, literally, doing the same thing...