Tried the 'no spoilers' rule in my book club and 3 people quit

Last month I suggested we try a no spoilers rule for our mystery picks, meaning nobody could talk about the ending until the next meetup. Two people said it made the discussion better because they actually had to describe the book without giving anything away, but three others got mad and said it killed the whole point of meeting up to hash out the ending together. We lost those three members by the second week, and now our group is down to five people meeting at the Panera on Maple Street. I learned that some folks come to book club to argue about the twist, not to protect it. Has anyone else tried a rule like this and had it blow up in their face?