Let's go through a typical First Answers review of a non-answer from the perspective of a new reviewer.
Here's what you see in the queue:
It looks to me like I should pick one of those actions on the right. It could certainly use a helpful comment. Let's pick "Share feedback":
Hmmm, those don't seem right. Let's click "Learn more" up at the top:
Hmmm, no, those don't apply at all. Okay, last try: let's click that "Read more" link at the bottom.
Check that the post author attempts to provide a focused answer, and not a simple comment or new question.
Aha! That's relevant! But...it doesn't say what to do with a simple comment or new question. So I guess I'll share feedback. It could certainly use additional details and some supporting information to make it answer the question, so either option works, really.
Okay, back to my own perspective. You and I know, because we've been around a while, that the correct answer is to click that little grey "Flag" link below the question, select "Not an answer", and submit the review as "Other action". But I have no idea how anyone is supposed to figure this out from looking at the queue interface.
And this isn't a hypothetical: Stack Overflow gets a constant stream of non-answers. We have an entire queue for them. But they're not going to end up there if people don't flag them. This one here (screenshot for those without 10k on Stack Overflow) stuck around for a week before anyone finally noticed, despite the reviewer clearly noticing something was wrong (they appear to have followed the process I described above). The asker even left a comment containing useful information about their question that will be lost upon deleting it (fortunately, it was also edited into the question, but this doesn't always happen).
Please provide clearer handling for these. Ideally, there'd be something that provides feedback to the poster and sends it over to the Low-quality Answers queue. But any improvement would be great.