Separate coming up with ideas and deciding
Many meetings try to do two things at the same time. In them we try to come up with ideas and we try to narrow down which of these ideas are the best ones. All at the same time.
As shown in the little story it's pretty confusing and frustrating when you do it all at the same time.
That's why I usually seperate the tasks in the meetings I facilitate. For example I will give the team 20 minutes to find as many different possible solutions. At this time, we don't discuss them, we just list them. When someone wants to critize, give feedback or give details I tell them: that comes after. Now, we build the list.
When the list is built, I then give some time to share feedback, vote and take a decision. At this moment, we can't add new ideas. We are just narrowing down.