A) Csv isn't actually a standard, so there's no one universal way of dealing with it (we can get really close). B) the keys and values are disjointed in csv as

A) Csv isn't actually a standard, so there's no one universal way of dealing with it (we can get really close). B) the keys and values are disjointed in csv as separate rows/columns, vs key:value C) yes flat is better but when you need nested, nested is useful