> 11 years from introduction, no one has come up with a use-case for blockchain
This seems an odd claim to make. Currently there's hundreds of Cryptocurrencies using blockchains as a foundation, and more than half a trillion dollars tied up in them. Right now it seems like they're at least speculative investments. If this does not count as a use-case then we'd better break the news to essentially all of finance.
Years ago before the values jumped you could do plenty of actual currency things with cryptocurrencies: there were ATMs, you could buy beers at a pub or pay for server hosting (something I did myself), etc. Because of all of the speculation cryptocurrencies have generally become too volatile for that. Nobody wants to find out at the pub there was a market crash and they can't cover their outing. At the time though, it all worked and had incredibly low transaction fees.
Then there's the applications for areas like logistics, supply chain, that are all under development. IMO it has absolutely established itself as a technology and like everything new people were quick to try to apply it to every problem and found it largely didn't fit most places. That doesn't mean it isn't useful.