Users generally don't want you to explain things, just tell them what to do. They may act like they want you to explain it, but they don't really want to hear the answer. Something like "Go back to the start button, and your app is gone until you need it again" works pretty well.
It's all about how and what you communicate. I have co-workers who are more likely to try to explain things too much, or take a path that they think is what the users need, and it never seems to work out. I don't know, maybe I just have a knack for it, but I tend to get much different results than other people when dealing with users.
I did first show her the "return to the start screen via the start button (on the keyboard)". Her first response was "I have to press a key to close it?!?!? Dumb." That's what lead to the explanation.
Maybe the simple answer is the right one: the end user's comments are justified.