I don't think you can judge the validity of an idea, or a technology, or anything really by looking at its (perceived) failures. The fact you don't think blockchains don't work for bank transfers, shares, currency, contracts, or whatever else doesn't mean they aren't useful. It just means no one has found a use that you think is appropriate yet, or they haven't persuaded you that you're wrong about any of the things you don't like.
The one thing that gives me a ray of hope about blockchain is git. A git repo is a very similar to a blockchain. It has blocks, and each block has a payload, and they're all chained together in a way that allows distributed additions. git looks, walks, and quacks like a blockchain. It's just lacking the consensus bit really. As someone who would gladly apply git to practically every problem in tech it makes me think that blockchains could be really damn useful if only people would stop trying to pretend they're the future of money.
Also that "the consensus bit" isn't a small thing that you just tack on to an existing system for very little cost. That bit turns something really efficient and widely applicable like git, merkle trees, etc. into a vastly more complicated and inefficient system.
What a really strange idea. Of course you can. What better way is there to judge a technology other than its failures and successes?
You reserve judging until you're sure that there's no possible route to success left, and for a reasonably general tech that's a really, really long time. You can judge the attempts along the way, so saying things like cryptocurrencies are stupid is fine, but to write off the entire technology as invalid and useless is going too far. Besides, you don't need to. It doesn't add anything to the conversation. You can just say "no one has found a good use for it" and leave it at that. Saying "no one will find a use" is pointlessly negative.
We've had 14 years of promises and so far, nothing. Why would any rational person believe you?
The one thing that gives me a ray of hope about blockchain is git. A git repo is a very similar to a blockchain. It has blocks, and each block has a payload, and they're all chained together in a way that allows distributed additions. git looks, walks, and quacks like a blockchain. It's just lacking the consensus bit really. As someone who would gladly apply git to practically every problem in tech it makes me think that blockchains could be really damn useful if only people would stop trying to pretend they're the future of money.