Notes:
We have already seen that the system as a whole can only be successful with many participants. So the scalability of the mechanism is of particular importance. As a technician, I would recommend a decentralised architecture for the technical kind of scalability.
But technical scalability is not enough, because the mechanism is meant to connect people. It shall connect different people. People with completely different attitudes. People with different cultural backgrounds. Old people and young people. People with selfish interests. People which might want you to buy something from them that you do not want.
So the mechanism also needs to be socially scalable. The users need tools to protect their own selfish interests against the interests of others. Thus the basic principle of the community shall be: everybody will say whatever s/he wants to, as long as nobody is forced to listen.
Another requirement I already mentioned is that the mechanism shall cope with multimedia content like audio, images and videos besides text messages. It also shall be interactive and it shall be responsive to user ratings.