An alfajor is a cylinder of chocolate, biscuit, and filling ((Dulce de leche, jam, and chocolate mousse are popular.)) that is Argentina's favorite desert or sweet snack. Imagine if the cupcake craze in the U.S. started two centuries ago and never stopped - that might provide some idea of the grip the alfajor has on the Argentinian desert market. Unlike cupcakes, you generally don't see people waiting in long line for alfajores, but that's probably because of how many bakeries there are. ((Honestly, there seem to be at least two successful, independently owned bakeries on every city block.)) Plus, an Argentinian's alfajor fix can also be satisfied at a convenience store or supermarket, where well-known confectionery companies like Milka sell their own prepackaged version of the treat.
Honestly, I don't see what all the fuss is about. The biscuit section is generally dry without being crispy and the chocolate often lacks taste. But maybe I've been going to the wrong places. There are, after all, a lot of options.