I think the trend started more with having training built into the program. Instead of a separate manual, which nobody reads, the program should be "intuitive". However, "intuitive" is very subjective. With standard UI rules being expandedbroken (FIFY) by mobile, sometimes people needed a little help to learn how to use the program. Having a quick 30 second tour of how to use a program could make the difference between someone immediately uninstalling it because they can't figure out how to use it and having a happy customer. That then grew into "look - a new feature" because if the user doesn't know it's there, then it will never get used. People are creatures of habit. If I never go to that particular menu, then I won't know that a new menu item is there. They teach this in software UI/UX classes at college.
Bond Keep all things as simple as possible, but no simpler. -said someone, somewhere