Functionality that is specific to a filetype should not be part of core, not everyone wants every language special functions cluttering up their editor. Plugins is the way all editors do it these days, [Atom](https://atom.io/packages/search?q=markdown), [Emacs](https://www.emacswiki.org/emacs/MarkdownMode), [Eclipse](https://marketplace.eclipse.org/category/free-tagging/markdown) etc