Blockchain technology is slow, it provides no means of transaction rollback, making it useless for the vast majority of real-world situations, it is easily subject to abuse and fraud, and crypto currencies enforced scarcity makes them useless as a means of commerce. There was literally no reason for them to exist at all outside of hype and maybe the desire to do crimes and not get caught — and even that is an overblown aspect of crypto currencies.
The 5 Biggest Problems With Blockchain Technology Everyone Must Know About