Ever come out of a meeting knowing that no person there has the slightest bit more information than they went in with? Of course you have. There's a documented reason why this is very likely to happen.
Scientists asked a group of people to meet together and discuss the resumes of people they were going to fake hire for a fake job. They had their choice of three candidates, and profiles of each were available to them all. There was also a hidden profile, only available to some of the people at the meeting. That hidden profile showed one candidate to be a clear winner. Out of 20 groups, only four picked the "best" candidate. The hidden profile stayed hidden.
Although meetings are supposed to be about pooling individual information, they can be dominated by the "shared information bias." Put people in a group, and they'll tend to spend a lot of time discussing information that everyone in the group already has, and either ignore or not mention new information. Sometimes this happens because the one person with new information won't speak up. They might have the right idea. People tend to form an opinion early in a group decision-making setting, and then justify it to themselves. They'll inflate and repeat information that supports their position, and disregard and belittle information that shows their initial decision might be wrong. Essentially, a group can easily get into a dynamic where they decide on the "right" decision early, with little information, and spend the rest of the meeting repeating their arguments to show how right they are.
It's hard to get out of this dynamic. Unfortunately for everyone who has suffered through a long meeting, one strategy is taking away deadlines. Make people feel pressed for time and they'll come to that initial decision early, and just keep doubling down. Let people talk long enough, and all the information might make it into the general pool. In the end, there's no substitute for everyone sincerely wanting to make the correct decision. So the problem with meetings will always be the terrible, terrible people participating in them.