I recently was looking up a question and noticed a small improvement I could make to an answer by adding an additional detail. The user whose answer it was told me that I should not have made this edit because the answer was a few years old.
Was this user correct? Are older questions and answers on the site not supposed to be edited? And if so, why not?
Edit: The nature of the edit was citing a theorem to explain an assertion. The assertion would be obvious to someone familiar with the material, but a novice would probably find the citation helpful. Hence, the edit was not merely a copy edit, but it did not substantially change the content of the answer, only the presentation.