> Maybe get fewer people in the meeting? Push as much discussion as possible out of the meeting so it only involves the people who care? More delegation and indirection?

Totally with you here. I also make it mandatory that everyone coming to a meeting read the offline discussion before hand. When someone shows up and we have to summarize the back history again it is selfishly wasting everyones time. I finally started refusing to do it and will leave and tell the PM to reschedule.