It's not just a good idea for HN. It's a good practice to apply in one's everyday life, generally.
Also, there are often cases when someone has an idea or thought that isn't necessarily framed with the right wording. That doesn't make the idea invalid and it is often worth exploring to understand what they were trying to express.
These things is a 'waste of time', in my opinion. In fact, it is often the direct opposite: A wonderful use of time.