Why are late answers from new users reviewed?
This simple question might appear somewhere in the meta FAQ or questions, but after searching for several minutes I can't find the logic clearly explained.
Anyone, not just new users, that answers an old question should be contributing to the existing body of knowledge already present with the other existing answers. Throwing it into the review queue is [in theory] a good way to check that. It also helps tease out gems and weed out poor answers.
The "Late Answers" review page is described with the following phrase.
Review late answers from new users
On Drupal Answers, the Stack Exchange site where I am moderator, many of those late answers are:
While not all the late answers are like this, between the late answers written by new users you can find answers that should be flagged as "not an answer." There are then answers that are only spam, which generally are written for old questions, even if I have also seen spammer using a question for spamming, and adding more spam as answers.
That is the reason why there is the Late Answers review page.
If then the post is a perfectly valid answer, nothing needs to be done (or the answer could be up-voted).