One way to earn Koin at the moment is by producing blocks (or joining a burn pool if you don't want to run the equipment yourself). You burn Koin for VHP which you produce blocks with. Unlike Hive, Koinos is not DPoS so anybody can be a block producer - you do not need to be voted in. In this aspect the consensus mechanism is more like PoW on Bitcoin.
There is not a rewards pool like on Hive and it is not a blogging platform. Someone could technically develop a smart contract with a different token that mimics this functionality, but, as far as I know no one has any plans for this type of thing at the moment. There are no middlemen, this is entirely decentralized tech. Koinos Group is one of the block producers on the network but they are not even the biggest one at the moment.