The paper seems like a high school science project, but in my experience one common reason for having a meeting is this: Person A wants Person B (Person C's boss) to tell Person C to do something. That's it. So Person A slacks or emails Person B saying I need to get Person C to do this thing. Person B says oh we better have a meeting. The three get onto the meeting and Person B says "yeah so Person A was talking about this thing, I'm not really sure what it is...". And the meeting ends with Person C saying "ok I will do that".

All of this can be avoided in my experience by creating a culture of task assignment. Often I've seen the bug/issue tracking system used to facilitate this but you can use other applications. In this scenario Person A would open a bug detailing what they want done, and either assign it, or put it in the triage queue so Person B get assigned next. Person B reviews, makes any notes, then assigns to Person C. That's it. No meeting.