To be honest, witness system will not work (in terms of contributing to the community). This happens to Bitshares before. See the current market cap of Bitshares comparing to that of its launch time. It will repeat in Steem (I mean the so-called contribution). There are witnesses just keep claiming what they have done. There is no proof, nor check and balance. Another problem is whether their contribution worthy for their payout. I strongly urge the community to turn more witnesses to miner-witnesses. At least the miners spend electricity to secure the network. Twenty something human witnesses can be easily colluded to harm the network.