Honestly, I agree with your idea, and sincerely I more than once have almost been a victim of this.
The thing is, when I start writing without an initial plan(you know, the one where you just start writing but you don't know where you are going), Finding an end to these kind of story always proves very demanding, and simply saying "it was a dream" can make the problem go away. But after reading most of @jayna 's writing tips, I know for sure that a perfect and can be anything except,"...and it was all a dream".