The mechanisms you mention regarding consensus are what distinguish a private database from a blockchain because a private database obtains consensus via controlling the nodes where a blockchain is uncontrolled and wide open to attack. It's that open nature, to me, that separates a blockchain from a database. The only thing protecting it is the incentive provided to the block producers to be rational actors in the best interests of themselves and the network. That incentive only comes through the distribution of a valuable token. I have yet to see any other mechanism for providing that incentive. I have seen blockchains with tokens of little value be 51% attacked. If the token is not valued enough, not enough miners will mine the blockchain to reach useful, secure consensus which means it will fail. I say "mining" here but similar economic incentives exist for DPOS as well.