For example, see this post on Academia (deleted now.) It's clearly intended to be a comment, but was posted as an answer. The content of the post is:
+1 to @ff524♦'s comment-I know that you have never heard of a university with an age limit on funding,you requested me to not post comments as answers as if I register my account (instead of deleting it),then I'll be able to comment on my own posts myself,but what I said about the stopping of the OP's fellowship is that if he cann't finsh his PhD before attaining the age of 35 years then he will never be able to complete it (trivial answer to be converted into comment to ff524♦'s post)
A new user account posted this, and it was pushed into the first posts review queue. Then the user deleted his own account (but not the post). A few minutes later, the review job is invalidated. The post is removed from the review queue without ever being reviewed, and escapes notice until 9 hours later.
The stated purpose of the First Posts queue
is to give special attention to users who may need to be educated on some aspect of our model and to posts that are more likely to need improvement.
Why should a potentially problematic post be removed from review, just because the person who posted it deleted his account? The post may still need attention.