I'd say if someone's enjoyment hinges on that first experience, of not knowing and then knowing, that piece of media isn't that significant or worthwhile. In the case of Star Wars, its the masterful melodrama in Empire Strike's Back that makes it special, the execution of all the plot points, rather than the plot points themselves.
Knowing spoilers ahead of time also increases tension, as you're anticipating the approach of something and that itself builds hype.