Through comments, a user has shown an understanding of the content and as well if there is anything that the author needs to correct would be pointed out. Social media is all about creating reasonable interaction which on the Steemit platform it is through comments that we can achieve. You have said it all. Comments are powerful.
That's true, we should be bold enough to point out to the commentator that he missed this point. I am sure this would alert him, but how many of us do that?