I think this is an excellent approach, and I try to do it myself. But YMMV for getting teammates to do it in a meeting - even with a generally supportive manager (not me, I'm just scrum master), there is just a psychological resistance. I don't think that they have a list in their heads and are simply afraid to share it, I'd guess that it requires some effortful imagination, and would be unpleasant, so things just get stuck. I'd love ideas for follow up prompts that might help with this.