People make meaningful contributions in group or public settings. People know what they want and need. Group processes are a valid technique to prioritise needs. The people who are able to make good contributions are willing to play the games of facilitators. The product of a good participative process will be sustainable.
People are willing to give up leisure time for voluntary activities for the community good.
Properly advertising a meeting means that the appropriate people will attend. People want to participate. Because a participative process met expectations in one context it will work in another.