The confusion about the use case of NoSQL probably stems from the term "NoSQL" being so vaguely defined. All you can say for sure about one is that it's not relational. But other than that there's not much in common between (for example) key-value stores, graph databases and object databases.
Result: The author has to qualify all statements with "only applies to some NoSQL databases".
Result: The author has to qualify all statements with "only applies to some NoSQL databases".