If this experiment works, it should benefit the people in El Salvador because they now have the option to transact and communicate their purchase preferences all around the globe instead of just to the people they meet in person. As for using normal banks, I reckon we had the whole 20th century to try that experiment. Now, banks seem a bit like hope-cope such that it seems like a matter of shitting in one hand and "could have been done with just like a public bank" in the other.