I truly believe that a large number of people need to have an audience from time to time (for self-esteem reasons), and many meetings are basically hostage situations in support of this goal
I've often seen it as possibly being used to distribute (IE: avoid) responsibility, and work.
Some people who don't know how to do their jobs just keep calling meetings with those who do, until those capable of doing the work just go ahead and do it, just to end the meeting torture.
And no decisions are a personal responsibility if they were made or reviewed in a meeting with others.