Murmuring Obols have long been one of Diablo 4's worst currencies. They're a good idea in concept—you complete an event out in the world, pick up some little blue coins, and take them back to a strange vendor in the city to trade for a specific type of loot. These Purveyors of Curiosities might give you a legendary or rare piece of gear, or they might give you some absolute garbage. It's all part of the gamble.
The problem with Obols is that they don't give you much you can actually use...