You should be able to do some pipe fu and carry out some form of merging via bash. I mostly use it for making our output more readable or producing CSV style reports with the filtered data. Its filters are probably the biggest feature, at least in my mind.
Sorry for not being clear. I meant a merge in the form of {"a": 1, "b": 2, "c": 3} merged with {"b": 20} returning {"a": 1, "b": 20, "c": 3}. Like Python's update() or PHP's array_replace_recursive() although PHP's a little richer.