Is the "crypto" part essentially arbitrary? Just a way to restrict the number of coins in existence and tie the value to some real-world work? People are like "back in the day it was folding proteins or SETI@home and now it's mining coins." Couldn't you make a currency where the "work" you put in isn't cryptography calculations, but cycles devoted to protein folding? Assuming you could record that stuff using a blockchain or whatever.