Well, it's a key-value data structure, serialized in the way you describe. You could say that a JSON object wasn't a key-value structure by the same logic. It's

Well, it's a key-value data structure, serialized in the way you describe. You could say that a JSON object wasn't a key-value structure by the same logic. It's the same way for structures serialized in binary rather than text, like BSON objects. You can think of a native dictionary as a declarative structure where each of the pairs "happen" simultaneously. A serialized structure is necessarily imperative because it must be an ordered series of bytes that are evaluated in sequence; it must be in order to be written to disk or sent across the network (with /proc being a sort of hybrid, IPC implemented as a virtual filesystem). So we generally need to convert our dictionaries into lists to serialize them. You might think of something like sending an entire SQLite database as an exception to this rule, but there's an equivalent perspective that it is an example of the rule instead. Lists of key-value pairs and dictionaries of key-value pairs are duals of each other so you're free to take the interpretation you prefer.