Do some user testing with casual computer users (not even pure novices), and watch as you ask them to complete a two step task with a file (like, say, resize and then email). They can usually figure it out, but it takes them a long time and they become frustrated. It's not a natural experience to them.
You know when you first start programming, and you hack together snippets of code to make your first program work? That's kind of what using a computer is like to the majority of people.