Or is it?

You never can go entirely back to zero. Until now all of the progress you’ve made it all counts for something. And this is precisely why we get so emotional at the end of a story, fictional or otherwise. We’ve invested ourselves into the stories, and we’ve seen how far the characters have come. That puts perspective on the story, and that’s where we feel the emotion.

It’s the same with back to zero. It may be a new beginning, but it’s a beginning with an emotional backstory, one we need to remind ourselves of as we get started.