Agreeing gives status to the author, disagreeing tries to give status to you.
A good way to agree is e.g. some kind of “yes, and”, where you add another example the original insight applies to. But that requires having a good example that the author missed.
Sometimes I do the low-status thing and just write a comment praising the article, especially if I see the discussion is either empty or that kind that you described.
Agreeing gives status to the author, disagreeing tries to give status to you.
A good way to agree is e.g. some kind of “yes, and”, where you add another example the original insight applies to. But that requires having a good example that the author missed.
Sometimes I do the low-status thing and just write a comment praising the article, especially if I see the discussion is either empty or that kind that you described.