What was the useful blockchain tech? It seemed to me to all be different ways of avoiding regulations or bypassing existing system or addressing issues that were already solved by using centralized systems.
i remember my friends excitedly telling me how cross border container trade is still done with paperwork because nobody trusts each others' IT systems. I'm pretty sure it still is because they can't be convinced to trust blockchain systems either.
trustworthy voting is another application. ive yet to see a political party that runs an internal voting system that doesnt rely upon you trusting a central server run by a few people. this is crazy.
It seems to me that people don't want to run their own security upon which they have no recourse if they fail, and don't think that benefits of centralized systems are worth giving up for the dubious benefits of a decentralized trust. Imagine if the scams for the currencies occurred with voting systems, with no way to undo it.
The technologies just didn't do anything that more than a small number of people wanted.