"If it is possible to imagine one private electronic currency, then its possible to imagine several, and there would be no guarantee that other people would accept the particular electronic money you use."
IMO this is an interesting issue that hasn't been addressed enough on this forum.
To me, there is no guarantee that other people would accept any currency anyway, unless they are forced to. Money should not get its value from coercion, but social acceptance. Moreover, even in a world with many competing cryptocurrencies, commercial transactions with anyone are possible, as long as there is an efficient currency exchange market.
Yes but in the BitCoin model (which is the first to solve the double-spend problem without relying on a trusted entity) there is a
massive first-mover advantage because everyone using the same blockchain gives everyone increased security compared to multiple blockchains. Without specific differentiating features it would be foolish to use anything but the most secure cryptocurrency--as a result electronic currencies will experience social selection amongst their
features, but
not arbitrary proliferation.
So in answer to the original quote there is indeed the best possible guarantee--a mathematical one.