You might draw comparisons to the stock market. The Dow Jones lost 90% of its value in the Great Depression, but we didn't do away with the stock market altogether. We fixed the structural problems because there is clear utility to the trading of corporate securities.
Currencies that lose 90% of their purchasing power tend to get replaced. Equities/securities? Not so much. I think the point is that Bitcoin is either a terrible currency, or not a currency at all but an equity.
Do they? I more often see a mere slashing of a few zeroes and maybe a slightly different name, but with the old one being convertible and keeping the same monetary policy.
