The one that chiefly got me started on it was that an outline that dies halfway through because there's no story there is rather less dispiriting than a story that does the same. Stories take a lot more work.
This is also a useful trait even in outlines that can come to an end if you work at it. Sometimes you have to slice out chunks of a story when it has gone awry, so that it will work in the end. Sometimes you realize the story needs to progress rather than keeping on with the same old old. Or even because it has gone dead and you have to try see what it was that made it go dead -- lopping out some of the last events to see if the inspiration comes back. It's a lot easier to do when the last three scenes are three sentences in the outline.