An example of leapfrogging is China's payment system which switched directly from a cash-only system to a mobile-payment system in the span of a decade, entirely bypassing the need for credit cards.
I believe that cryptocurrencies, ironically, are leaving the unbanked populace behind by being a payment-only system instead of being a payment-credit system. If Bitcoin is truly successful and replaces Visa and MasterCard -- both of which also operate as a credit system -- then that's just going to result in slower economic growth in underdeveloped countries.