Flagging doesn't mean deleting. It brings those non answers to attention.

I spent an hour looking through them today and I've only seen one false positive and of course someone reported it instantly.

It's pretty useful. One of the questions I saw today was from few years ago and no one had answered it. Someone added a "me too" answer that wasn't helpful. I flagged that answer and provided a new answer to the question, and now it may help someone in the future.