Another angle of criticism would be that solving the Byzantine generals problem with the threat model that cryptocurrencies target (i.e. anyone can join and lea

Another angle of criticism would be that solving the Byzantine generals problem with the threat model that cryptocurrencies target (i.e. anyone can join and leave the network somewhat anonymously at any time) is simply not necessary in the real world unless you are a die hard anarchist. Therefore, for any application that doesn't have those requirements it is a huge waste of resources.