If I understand it correctly it should be primarily useful in methods attempting to extract flavour from something. Maybe tea, spices like cinnamon, maybe vanilla but thats fairly soft so it mightn't work very well.

Well, usually the heat is being used to actually chemically change the food. Coffee beans are pre-roasted and you're just using hot water to get the coffee into the liquid. It's not like this technique could be used to cook meat or vegetables. Liquefy them, possibly.