Ask HN: Convince me of a blockchain's utility

It seems to me that blockchains have no real value, and all of the potential applications of blockchain tech seem like they could be accomplished more easily and efficiently with a traditional database. Part of my problem with blockchains is the premise - taken for granted by blockchain enthusiasts - that 'centralized data' is bad, and the salvation wrought by blockchains through 'decentralized data' is a major source of their utility. First, data being controlled by a single entity is not a problem. In fact it promotes the curation and management of that data, which is a good thing. Second, the concept of data decentralization, forgetting for a moment that it addresses a problem that doesn't exist, doesn't really make economic sense. A data oriented business provides value by gathering and managing data that was not previously available. Ownership of that data and the associated promise of profit is the incentive necessary to motivate the work of gathering and presenting data in a workable format. No one who wants to build a data oriented business will ever want to 'decentralize' their data, because then they're basically giving up ownership. Is my appraisal of the data (de)centralization issue correct? Why? Where does a blockchain add real value? What does it enable that was not previously possible? How does it improve over existing solutions?