Why are team meetings such a waste of time?

The reason is that we are humans, social animals.
A person, if alone, can focus on what he does and can focus on the topic to think about. He doesn't have to co-ordinate people, but he has to co-ordinate his senses. He can be more productive.
While in groups, we tend to 'socialize', do some gossip, and talk unnecessarily such that we always divert from the topic. Also, we have to face egos, superiority and inferiority complex, we fight on irrelevant topics, and its hard to co-ordinate people. So, we talk and think more irrelevantly than when working alone!
Also, in a group, if someone brings out an idea which may be a bad one, but the oratory would do the trick, the higher people will tend to accept that idea. Sometimes, even if it is a good idea, the others start thinking on those lines and thus do not encourage their brains to think in a different way to have a better idea. Seniority and reputation plays a major part in group discussions in some cases!

P.S.: If you ask whether I agree or not that team meetings are such a time waste. I would say a 50:50. Because much depends on the team and the coordinator in charge!

Depends (as usual 😛 )

My university satellite project definitely needed team decisions because of the multiple subsystems that are dependent on each other (sensors, OBDH, power, comms, structure, etc). It required unified approaches that everyone agrees upon, and making sure each team member is keeping up with the development pace. Quite tough, considering the tight deadlines and budget. Its true that people can impose their ideas (good or bad) on people while in groups.. but I was blessed with a great team of friends that accepted constructive criticism, thought logically, and were supportive of each other. Fun times indeed 😉