I state that it is a misuse of the tool if your backlog contains tasks instead of goals. There is a rational behind it, so more task-oriented people usually understands why it is a good idea after being presented the reasoning, and they marvel at this fresh and new concept.
However, it is not a new concept. The old idea behind a Work Breakdown Structure pretty much sums it up: you decompose the thing you want to build (the goal) into parts, and the appropriate level of decomposition is given by the ability to make deliveries in between. The sprint size, if you like.
I recommend the Wikipedia article on WBS to anyone interested in Product Ownership.