I have the opposite opinion. Writing comments for (in-person) interviews is silly and a sign of wasting time. Interviews in general are not designed to check your coding style, but your ability to solve problems, whether they be reasonable or not.

Your comment is a little bit along the lines of, "if you the candidate didn't use a versioning system, I wouldn't hire him". It's just not what is being tested.

Now, if it was a "here are some problems, solve them and get back to us" type of interview, then sure, I would agree with you.