Can Decentralization Exist Without Blockchain?

More specifically - can decentralized justice/dispute resolution exist without blockchain technology, or would that just be Online Dispute Resolution? Kleros brings interesting insights to decentralized arbitration. It is built on Ethereum and handles smart contract disputes. However, can a platform such as Kleros, with its use of crowdsourcing and game theoretic incentives, work without blockchain but still be decentralized?