For the economic impact of monetary systems, the main role of currencies is handling credit - handling direct transactions is intuitively the direct application, but the impact of transaction costs ('costs' in the economic theory sense, not only the direct expenses but also any barriers, difficulties, risks, etc) on the economy, while significant, is not as huge as the impact of availability of credit and supply of money.
For example, when considering dollars, having the possibility to detach the dollar from the gold standard was so extremely valuable to the economy that all the possible transaction costs with handling paper or coins are a rounding error compared to that. Enabling fractional reserve banking is an immense effect on the productive output, due to the big increase in productive investment it enables, so it matters a lot whether a monetary system can support that. Historical changes to what metals were used for coins had a huge impact on economy not because of some decrease in transaction costs but because of changes to money supply. Etc.
At it's core, the primary function of finance is (and arguably has historically always been) handling debt, not handling transfers. So evaluating a currency system on the basis of how good it is for transactions is kind of putting the cart ahead of the horse, if the nature of that currency has, as most cryptocurrencies do, a major impact on the money supply (and thus handling debt).
For example, when considering dollars, having the possibility to detach the dollar from the gold standard was so extremely valuable to the economy that all the possible transaction costs with handling paper or coins are a rounding error compared to that. Enabling fractional reserve banking is an immense effect on the productive output, due to the big increase in productive investment it enables, so it matters a lot whether a monetary system can support that. Historical changes to what metals were used for coins had a huge impact on economy not because of some decrease in transaction costs but because of changes to money supply. Etc.
At it's core, the primary function of finance is (and arguably has historically always been) handling debt, not handling transfers. So evaluating a currency system on the basis of how good it is for transactions is kind of putting the cart ahead of the horse, if the nature of that currency has, as most cryptocurrencies do, a major impact on the money supply (and thus handling debt).