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There are some real benefits like resilience. Most people haven't yet understood that it's not enough to make the system better than centralized services. Slowly people are starting to realize that. There aren't really that many actually useful blockchain services currently – if it was easy to build on top of a blockchain, there would be lots of usecases by now.

Depends if you mean a potential use-case or a fully-developed use-case. See the thing about a chain is the elimination of all-too-human casual dishonesty. In this way a blockchain is an augmentation of ourselves.

I mean real world usecases. Bitcoin has proven that money can be build on top of a blockchain. Steem has proven that a publishing platform can be done. But that's about it, not much other examples.

The problem is that blockchains can only process information. Humans can still decide whether or not they use that. For example, you could make a lock that uses blockchain. But thiefs don't care if the lock is controlled by real key or blockchain – they go through the door if they want to. Or we can but our elections to the blockchain – but politicians will be still corrupted and there will be still people who don't respect the outcome.