Well, blockchain is sort of a new technology, but it's one that solves a problem that wouldn't be faced in a leftist future. The goal of blockchain is to create a fully decentralized system in the absence of trust between actors. But a communist has no need for decentralization; the state can act as a central authority to maintain the system. And an anarchist has no need for decentralization without trust; anarchists can simply gather together for key-exchange meetings, allowing them to know which keys represent which actors, and assign the appropriate level of trust to each.