It'd be interesting to see this study replicated in some way with people who self-identify (like we're seeing in the replies here) as people who either like, don't like, or don't mind spoilers in general.

I think there's a selection bias in using undergraduates to support this point. They probably appreciate the timesaving element and somebody telling them what the important bits are before they begin. Among other issues.

I also think there's a huge difference in time investment (and, to my way of thinking, that will directly impact this enjoyment measurement) when you talk about short stories vs. a novel, a series of novels, or a TV series.

But it's definitely an interesting article (as is the rebuttal Nate posted). I think another reason people don't like spoilers on the internets is oftentimes they've actively worked to avoid spoilers (and delayed the gratification of reading/viewing something they want to so as to avoid the possibility of having something spoiled) and then are frustrated to have spoilers appear in unlikely places, making their effort feel wasted. So it's not all about enjoying the story less, but other psychological elements at play.