Too Long; Didn't Read
Human beings are not very good at seeing into the future. Trying to predict when an event will happen with any degree of accuracy is very difficult. Story points are not a silver bullet that will let you make perfect predictions about when a task will be finished, but in my experience, they are a significant step up from trying to estimate time directly. They help you shift from hand-waving and guessing, to evidence-based reasoning about a teams capacity. The accuracy of story point-based predictions tend to improve as teams gain practice.