Say you've just had a great idea for a new web app. An app that's never been done before. An app that will improve the quality of life of millions of people. An app that will make you rich and famous.
You spend the weekend coding like crazy, and at 4:30am Monday morning, you have something that runs, barely. Most of the bad crashes are fixed, but you still see some weird bugs every once in a while. You're too sleepy to debug these issues now, but every second that your app isn't online is an opportunity for somebody else to snatch up your great idea.