The pitfall is that JSON has zero guarantees for how often line breaks do and don't occur, and is often used to represent hierarchical data. Grepping for 'key: foo', and some liberal use of -A and -B may find you what you're looking for, but grep is simply the wrong tool for that job. (And how do you handle a key with newlines in it?) jq [0] is the right tool, but jq's syntax is it's own, and is harder to use (unless you use it regularly).

[0] https://stedolan.github.io/jq/