I am all for minimalistic design. And Medium’s text editor is a joy to work with, so I am not really complaining. I’m also familiar (and mostly agree )with the school of thought that limitations on choices free a person up to get more done. Still, there’s a fine line between granting your users freedom by limitation on choice, and just plain limiting your users.
Or maybe I’m nitpicking about a personal preference. I just like centered headers more than left aligned. Specially If you got a short title.