All of those transaction costs can be handled by decentralized communication backed by reputation systems. Blockchains are great platforms for reputation system

All of those transaction costs can be handled by decentralized communication backed by reputation systems. Blockchains are great platforms for reputation systems. We will soon see that while it's hard to get systems off the ground that require network effects, making them entirely open and run by no one makes them a great choice for developers and consumers. I expect that decentralization yields its own sort of network effects.