Bitcoin is the first "voluntary consensus" system I think we've seen. Other systems may be centrally decided or democratically decided, but in all cases once a decision is made you have to follow it. For example we have:

• The FED - Small group of people make all decisions. No one else has any influence over said decisions. Once a decision is made, everyone is forced to follow the FED's decisions or go to jail.
• Democracy - Large scale popularity vote, everyone gets to include their voice (in theory, we all know there are problems in today's "democracy"). Decisions (in theory) follow the opinion of the majority. Once a decision is made, everyone is forced to follow the decision or go to jail.

In both cases, once a decision is made you have to follow it or go to jail.