It is certainly best practice.
There have been many occasions when I've reviewed, particularly Late Answers, where the post merely duplicates an existing answer.
Sometimes an answer from a new user is a comment on an existing answer but doesn't directly reference that answer.
By making checks like this you can add better, more detailed comments as feedback to the poster. This comes across a little more friendly than simply The does not answer the question. Even if you still flag it as NAA or VLQ.
