Is that possible? Or must usefulness and non-obvious be completely independent arguments?
For example, if an invention was never invented because everybody thought it would be a useless invention, would it be non-obvious if someone invented it and discovered its usefulness perhaps in some obscure scenario?
Also, referencing the first answer to: When is combining prior art to invent something new obvious and when is it not obvious?
If A produced output X and B produced output X, but the combination of A + B produced 10X, then it is a non-obvious combination. Would this be an example of using usefulness to prove non-obviousness? We can assume that the combination A + B is mechanically obvious, etc.