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

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? 14 years is a very, very short amount of time.