Well, almost everything. If I have to edit in a simple text editor then I still prefer Markdown and of course syncing files is up to the user (I use a private Gitlab account). Hebrew text that spans a newline is also problematic in Emacs, despite ostensibly fully supporting Unicode. But these limitations are trivial compared to all the issues I've identified in all the newer apps. It turns out that two decades of development really does lead to a mature product.