Ask HN: Worst annoying usability habit of all times?

Why is it that most online application designers deem it necessary to add an annoying blinking distraction on the screen? This is usually in the form of a button that says "saving" and "saved" while changing color. You can see this in WorkFlowy for instance. Why? Do these designers ever use their own products seriously? Don't they realize that when we write we are trying to CONCENTRATE? You don't need to tell us that you saved the file every few seconds. Why put a blinking thing to annoy the user? Why? Why? Why?