My biggest issue with all the investment in blockchain-derived technologies that aren't cryptocurrency related is that it's hard to apply proof-of-work systems to real world problems. How do you incentivize people for mining blocks? How do you ensure you have enough distributed computing power, so that a single actor can't take over the entire network? The company using a blockchain to track diamonds is a good example. Do I get diamonds for mining blocks? Then what's the point? Companies like Everledger claiming to run a "private blockchain" are only using the word as marketing bullshit, because that effectively becomes a centralized database/linked list.