If your data is a User object with maps and arrays, and you design a data structure which gets you the result in exactly that format, you _are_ giving up the ab

If your data is a User object with maps and arrays, and you design a data structure which gets you the result in exactly that format, you _are_ giving up the ability to ask other questions of this data. You are giving up the ability to ask _many_ different kinds of questions (expressive) in a relatively simple way (concise).