There is nothing wrong with using vim's intentionally built in extension mechanisms.
There is nothing wrong with using them, except that (as the article points out) they don't work terribly well, take a lot of effort to get right, and aren't the focus of the editor.
Sublime and Emacs are joys to extend versus Vim, that doesn't mean it can't be done, just that it is tough.
Vim is good at editing text, is extremely portable, and works great with a partner in crime like tmux.
I have used vim for 12+ years, and the complexity of his setup makes me a bit dizzy.