Off hand, I don't think we had the computing power and memory in the 80s and 90s  to make a cryptocurrency like Bitcoin for the common man. Perhaps, a DPOS blockchain or some new altcoin crypto that is not heavy on memory and CPU power. 

We could have had something in the early 2000s perhaps. There was folding@home which was one of the original distributed computer systems. If someone had thought up Nakamoto's system, there were enough computers and Internet users out there to experiment with a Bitcoin like system in the year 2000.