See I disagree with your analogy. I think that applies to the spoiler thread, which is where people who have seen the movie and want to discuss what happens/what they enjoyed/etc. go. If you are going to a book club, it is assumed you read the story, just like the spoiler thread. These threads tend to be much more about discussing the larger context of the movie (i.e. how it does). I think it's unfair to say people who have not seen it can't have any interest in the overall success of the movie and discuss where it's at/how it did. I think the financial failure of this movie is a pretty large story. Both people who wanted to see it and didn't want to see it all predicted it to hit a billion on the low end. The fact it didn't is a story. The people interested in the larger story also deserve a place to also discuss things, especially as it relates to the industry as a whole.